Selected material from the Autism Diagnostic Observation Schedule, Second Edition (ADOS ®-2) manual.

Copyright © 2012 by Western Psychological

Services (WPS®). Provided by WPS for the sole purpose of introductory reference by qualified professionals. Not to be reprinted, excerpted, or
distributed in whole or in part without the prior written authorization of WPS (rights@wpspublish.com). Full materials available for purchase at wpspublish.com.

Chapter 1 Introduction

The Autism Diagnostic Observation Schedule, Second Edition (ADOS‑2) is a semi-structured, standardized assessment
of communication, social interaction, play/imaginative use of materials, and restricted and repetitive behaviors for
individuals who have been referred because of possible autism spectrum disorders (ASD). The ADOS‑2 is a revision of the
Autism Diagnostic Observation Schedule (ADOS; Lord, Rutter, DiLavore, & Risi, 1999), which has been referred to as the
“gold standard” observational assessment for diagnosing ASD (Kanne, Randolph, & Farmer, 2008; Ozonoff, Goodlin-Jones,
& Solomon, 2005). Information on the historical development of the ADOS can be found in Appendix A.
The ADOS‑2 contains five assessment modules. Each module offers standard activities designed to elicit behaviors
that are directly relevant to the diagnosis of ASD at different developmental levels and chronological ages. Protocol
Booklets guide the examiner through administering activities, coding observed behaviors, and scoring the algorithm.

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Features new to the ADOS‑2 include the following:

 Updated manual and protocols for all modules, with improved guidelines for administration, coding, and
interpretation
 Revised algorithms for Modules 1 through 3

 Comparison Score for Modules 1 through 3

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 Toddler Module and associated algorithms for assessing children at the youngest ages

The following introduction provides an overview of the ADOS‑2. Experienced ADOS users may wish to skip to the
section titled “Updating to the ADOS‑2 for Experienced ADOS Users.”
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Materials
The ADOS‑2 can be used with individuals at a wide range of developmental and language levels. One of five modules
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is chosen to be administered on the basis of the individual’s expressive language skills and chronological age, and the
appropriateness of assessment materials for the individual’s maturity level. The examiner makes a tentative decision
about which module to administer in advance of the session. After the session has begun, however, the examiner
may discover the need to switch to a different module that better matches the individual’s observed language level.
Guidelines for selecting and administering each ADOS‑2 module are presented in chapter 2. Because of the flexible
manner in which ADOS‑2 materials are used, it is essential that examiners have a full understanding of all of the
ADOS‑2 module protocols and materials.
The ADOS‑2 includes four components:

Manual
The ADOS‑2 Manual (WPS Product No. W-605M) is presented in two parts. All users of the ADOS‑2 should
familiarize themselves with both parts of this manual.
ADOS‑2 Manual (Part 1): Modules 1–4. Part 1 includes an overview of the ADOS‑2 as well as administration,
coding, interpretation, and instrument development/psychometric information pertaining to Modules 1 through 4.
Although this part is focused primarily on Modules 1 through 4, it presents general guidelines relevant to all five modules.
ADOS‑2 Manual (Part 2): Toddler Module. Part 2 follows the same structure as Part 1 and is focused specifically
on the Toddler Module. The Toddler Module is a major addition to the instrument, facilitating more accurate assessment
of younger children. As the assessment of very young children presents its own unique challenges, the presentation of
material for the Toddler Module was given the benefit of its own separate part.

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 Protocol Booklets for Observation, Coding, and Scoring the Algorithms
Each ADOS‑2 module has its own Protocol Booklet, which provides order and structure to the administration,
coding, and scoring of the module. The Observation section is used by the examiner during the session to guide the
presentation and observation of activities and to take notes. The Coding section is used immediately following the
session, when the examiner makes overall ratings based on the individual’s observed behavior. Upon completion of
coding, the Algorithm form is used to facilitate scoring. An overview of the ADOS‑2 modules is provided in the next
section, and detailed guidelines for selecting and administering each module are provided in chapters 2 and 6.
The five Protocol Booklets are as follows:
Toddler Module (WPS Product No. W-605A). For use with toddlers who are 12 to 30 months of age and who do not
consistently use phrase speech.
Module 1 (WPS Product No. W-605B). For use with children who are 31 months and older and who do not
consistently use phrase speech.
Module 2 (WPS Product No. W-605C). For use with children of any age who use phrase speech, but who are not
verbally fluent.
Module 3 (WPS Product No. W-605D). For use with verbally fluent children and young adolescents.
Module 4 (WPS Product No. W-605E). For use with verbally fluent older adolescents and adults.

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Kit
The ADOS‑2 kit (WPS Product No. W-605) is an integrated five-module kit that includes all the interactive stimulus
materials needed to administer each ADOS‑2 module, along with the ADOS‑2 Manual and a set of Protocol Booklets for
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each module. Note that many of the stimulus materials are used across modules. The ADOS‑2 kit contains a large number
of materials that have been carefully selected and reviewed by the authors to fill the multifaceted behavioral demands of
each ADOS‑2 activity. The examiner uses these materials to attract and structure the attention of the examinee during the
assessment. More information about administration materials for each module is provided in chapters 2 and 6.

Training Materials
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The ADOS‑2 is a highly structured observational assessment that requires specific, formal training. The “Principles
of Use” section later in this chapter provides information about the background and training necessary for proper use
of the ADOS‑2. WPS offers in-person clinical workshops on the ADOS‑2. Details about these workshops can be found
on the WPS Web site, www.wpspublish.com, or by calling WPS customer service at 1-800-648-8857. Alternatively, a
Training Video Program (WPS Product No. W-605DVD), which includes training videos and a guidebook, is available
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for use with the ADOS‑2. The Training Video Program is presented in two parts, which correspond to the two parts of
the ADOS‑2 Manual.

Training Video Program (Part 1): Modules 1–4. Part 1 of the Training Video Program is for use with Modules 1
through 4. As the ADOS‑2 retains the same basic activities and codes from Modules 1 through 4 of the ADOS, the
case examples presented in the videos for Modules 1 through 4 have not changed for the new edition. Part 1 of the
guidebook, however, has been updated from the previous Training Videos Guidebook to correspond to the revisions
made to the Protocol Booklets, including updates in activity instructions, coding, and scoring.

Training Video Program (Part 2): Toddler Module. Part 2 of the Training Video Program is for use with the
Toddler Module. It includes new video examples of Toddler Module administrations as well as corresponding guidebook
text with detailed explanations of coding decisions. Use of Part 2 presumes that the examiner has already completed
training in Modules 1 through 4.

Description of the Instrument

The ADOS‑2 consists of standard activities that provide the examiner with opportunities to observe behaviors that
are directly relevant to the diagnosis of ASD at different developmental levels and chronological ages. The ADOS‑2
incorporates the use of planned social activities, referred to as presses (Murray, 1938), that provide standard contexts in
which social interactions, communication, and particular types of behaviors are likely to appear. Each ADOS‑2 module

4 Part I: Modules 1–4

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 comprises social-communicative sequences that combine a series of unstructured and structured situations; each
situation provides a different combination of presses for particular social behaviors.
The ADOS‑2 has five modules, each of which can be administered in 40 to 60 minutes. Each module has its own
protocol, which contains a schedule of activities designed for use with children or adults (“participants”) at a particular
developmental and language level, ranging from 12 months of age and no expressive language to verbally fluent adults.
Only one of the five modules is administered and interpreted for an individual at any given point in time. The modules
are labeled T, 1, 2, 3, and 4, with each activity numbered within its module.
The examiner selects the module that is most appropriate for a particular child or adult primarily on the basis of the
participant’s expressive language skills, and secondarily on the basis of chronological age and/or the relevance of tasks
to the participant’s interests and abilities (detailed guidelines for selecting a module and determining a participant’s
expressive language level can be found in chapters 2 and 6). The Toddler Module (Module T) is designed for very young
children whose expressive language is consistent with the demands of Module 1 but who are between the ages of 12
and 30 months (see Part 2 of this manual for further details). Module 1 is intended for participants who are 31 months
and older who do not consistently use phrase speech. Module 2 is intended for participants of any age who use phrase
speech but who are not yet verbally fluent.
Modules T, 1, and 2 were developed for use with children, so the activities and materials may not always be
appropriate for older adolescents and adults. Although Modules 1 and 2 may be administered to older adolescents and
adults whose expressive language level is most appropriate to these modules, the results must be interpreted with
caution, because the validation samples for Modules 1 and 2 did not include older adolescents and adults. Suggested

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modifications for administering Modules 1 and 2 to an older individual with limited language are offered in chapter 2.
Both Modules 3 and 4 are intended for participants who are verbally fluent. Module 3 is best suited for children and
younger adolescents (usually under 16 years of age), whereas Module 4 is best suited for older adolescents and adults.
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The main difference between Modules 3 and 4 is that Module 3 employs observation during interactive play along with
the use of interview questions to gather information about social communication, whereas Module 4 depends primarily
on interview questions and conversation.
On the basis of observations made and notes taken during administration of the ADOS‑2, overall ratings (i.e., codes)
are assigned. These ratings are made immediately following the session, based on the live administration. The codes
are then converted to algorithm scores and used to complete a diagnostic algorithm (i.e., a selection of items that are
summed and compared with predetermined cutoff scores, or ranges of concern in the case of the Toddler Module),
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which can be used in conjunction with other information to formulate a clinical diagnosis.
The ADOS‑2 offers separate diagnostic algorithms for the different modules, and in some cases, for specific age
ranges and/or language levels within modules. The interpretation of these algorithms is discussed in chapters 3 and 7,
and copies of each algorithm form can be found at the end of the Protocol Booklet for each module. The algorithms
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for Modules 1 through 4 use cutoff scores for determining measure classifications (discussed in chapter 3), whereas
the Toddler Module algorithms provide ranges of concern that can assist examiners in formulating their clinical
impressions (see Part 2 of this manual for further details).
A Comparison Score is also offered for Modules 1 through 3, which provides a way of indicating a participant’s level
of autism spectrum–related symptomatology, as observed during the ADOS‑2, compared with that of children with
ASD who are of the same chronological age and language level. The Comparison Score can also be used to interpret an
individual’s own change in autism spectrum–related symptoms over time. Information about the interpretation of and
research basis for the Comparison Score is found in chapters 3 and 4.

Principles of Use
Professionals using the ADOS‑2 should have prior education, training, and experience that includes the use of
individually administered test batteries as well as extensive exposure to ASD. While a variety of specialists will use the
ADOS‑2, their use of results in writing reports and making recommendations should be consistent with professional
activities within their fields. For example, clinical psychologists and physicians might use the ADOS‑2 to inform
medical diagnoses; school psychologists might use results to inform special education classification; and occupational
therapists and speech and hearing professionals might use results for treatment planning. In all cases, each professional
who uses the ADOS‑2 must ensure that his or her credentials, background, and training are adequate for the intended
purpose.

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 When using the ADOS‑2, examiners need to be sufficiently familiar with the activities and codes so that they can
focus their attention on observation of the individual being assessed, rather than on administration details. This requires
practice in observation and coding, as well as in administering the activities. Before using the ADOS‑2, examiners
should thoroughly familiarize themselves with both Parts 1 and 2 of this manual, including the specific coding
instructions contained in the Protocol Booklets. In addition, valid administration of the ADOS‑2 requires training
specific to the instrument, which can be accomplished either by taking an in-person clinical training workshop
taught by an ADOS‑2 independent trainer or by using the WPS ADOS‑2 Training Video Program described earlier in
this chapter. WPS regularly sponsors in-person clinical training workshops taught by ADOS‑2 independent trainers.
Information can be found on the WPS Web site, www.wpspublish.com, or by contacting WPS at 1-800-648-8857.
Even given a sufficient educational background and experience with ASD, simple attendance at a workshop or
completion of the video training package is not sufficient to ensure competent use of the ADOS‑2. It is also critical for
examiners to practice using the ADOS‑2 on cases that are not part of formal evaluations and to bring themselves to
complete familiarity with the assessment activities and complete confidence that they can apply the coding categories
accurately. The amount of practice necessary for each examiner will vary, as it is dependent on each examiner’s prior
experience with ASD, in making formal observations, and in administering individual assessments.
Examiners who are involved in formal research directed at producing articles for publication in peer-reviewed
journals must additionally take a research training workshop followed by exercises that establish item coding accuracy
to a specific criterion. This heightened level of accuracy is needed to ensure that item-level coding is comparable at
different labs in different parts of the world where research is being conducted. Although WPS is not directly involved

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in research courses, links to relevant course information can be found on the WPS Web site. The WPS Web site also
provides links to other resources maintained by the authors, such as reference information for recent research
publications on the ADOS‑2.
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The ADOS‑2 is only one component of a full diagnostic evaluation for ASD. It provides information only on current
behavior and is based on a limited time sample. Assessment of ASD, like the assessment of other disorders, requires
the evaluation of multiple domains of functioning with several instruments and the collection of information from
multiple sources. Practitioners using the ADOS‑2 must remember that information from this instrument should never
be used in isolation to determine an individual’s clinical diagnosis or eligibility for services. For a comprehensive
clinical diagnosis, additional information will be required from a developmental history and often from a more
lengthy observation, as well as a detailed interview such as the Autism Diagnostic Interview–Revised (ADI-R; Rutter,
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Le Couteur, & Lord, 2003) or other caregiver interviews or questionnaires such as the Social Communication Questionnaire
(Rutter, Bailey, & Lord, 2003; see also Corsello et al., 2007). Additionally, information about an individual’s cognitive
and language abilities are necessary to interpret communication and social behaviors for the purposes of making
a clinical diagnosis of ASD (see Gotham, Bishop, & Lord, in press, for a discussion of best-practice guidelines for
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assessment of ASD).
It should be noted that this section provides the recommendations of the ADOS‑2 authors regarding proper
preparation and subsequent use of the ADOS‑2. As with the original ADOS, however, the ADOS‑2 is likely to be used
nationally and throughout the world, and local professional organizations or licensing authorities may have additional
or somewhat differing recommendations. The present discussion may be used to inform groups making rules or
regulations, but users must always recognize and adhere to the local rules that may govern their professional practices.

Updating to the ADOS‑2 for Experienced ADOS Users

This section provides experienced ADOS users with a brief overview of changes to the ADOS‑2 and materials and
training needed for ADOS‑2 administration. For a more detailed description of the features of the ADOS‑2, see the
earlier sections of this introduction.

Improvements in the ADOS‑2

Updated manual and protocols. The ADOS‑2 Manual is organized into two parts. Part 1 includes an overview of
the ADOS‑2 as well as administration, coding, interpretation, and instrument development/psychometric information
pertaining to Modules 1 through 4. This part of the manual corresponds most closely to the original WPS-published
ADOS Manual, and all of the information has been updated for the ADOS‑2. Although Part 1 is focused primarily on

6 Part I: Modules 1–4

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 Modules 1 through 4, it presents general guidelines relevant to all five modules. Part 2 follows the same structure as
Part 1 and is focused specifically on the Toddler Module.
The requirements for administration and coding are considered to be “functionally identical” between the ADOS
and ADOS‑2. Modules 1 through 4 retain the same basic activities and codes of the ADOS, but protocols have been
improved to clarify and improve administration guidelines and codes. The intention of these revisions is not to change
the meaning of the administration or coding, but rather to clarify points of common confusion. For this reason, all
prior administrations of the instrument can be taken as base data for analysis and interpretation. An overview of the
improvements to the Protocol Booklets is found in Appendix B in Part 1 of this manual.

Revised algorithms and Comparison Score for Modules 1 through 3. Fundamentally new to the ADOS‑2 are
the procedures involved in the algorithm computation and the Comparison Score for Modules 1 through 3. These new
procedures substantially improve the accuracy and effectiveness of the results of the instrument. The algorithms for
Modules 1 through 3 were revised for the ADOS‑2 on the basis of the findings of recent validation research (Gotham
et al., 2008; Gotham, Risi, Pickles, & Lord, 2007). The updated algorithms were developed using a larger, more
heterogeneous sample than was available for the original ADOS algorithms and are intended to provide improved
sensitivity and specificity (see chapter 4). The ADOS‑2 algorithm for Module 4 is identical to the Module 4 algorithm of
the ADOS; it has not been revised for this edition because older adolescents and adults were thought to merit individual
study and there were not sufficient data samples available for analysis. The new Comparison Score for Modules 1
through 3 provides a way of indicating a participant’s level of autism spectrum–related symptomatology, as observed
during the ADOS‑2, compared with that of children with ASD who are of the same chronological age and language

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level. The Comparison Score can also be used to interpret an individual’s own change in autism spectrum–related
symptoms over time.

Toddler Module. The ADOS‑2 now includes a Toddler Module, which is designed for very young children whose
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expressive language is consistent with the demands of Module 1 (i.e., they do not consistently use phrase speech),
but who are between the ages of 12 and 30 months. In contrast, Module 1 is now intended for participants who are
31 months and older who do not consistently use phrase speech. The Toddler Module has its own algorithms that
provide “ranges of concern” instead of cutoff scores. See Part 2 of this manual for detailed information about the
Toddler Module.
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ADOS‑2 Kit and Training Recommendations
Kit. The ADOS‑2 kit is an integrated five-module kit that includes all of the materials needed for the administration
of each ADOS‑2 module, as well as the ADOS‑2 Manual and a set of Protocol Booklets for each module. For professionals
who already have access to an ADOS kit, an upgrade kit is available that will provide the additional materials needed to
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become updated to the ADOS‑2.

Training. Clinical users of the ADOS‑2 who have already been trained in the ADOS can update themselves to
the ADOS‑2 by thoroughly familiarizing themselves with Parts 1 and 2 of this manual, giving special attention to
the updated administration and coding language provided in the administration chapter and Protocol Booklets for
Modules 1 through 4, the new Comparison Score and extended interpretive guidance, and the new administration and
coding guidelines for the Toddler Module. In addition, examiners who will be administering the Toddler Module should
use the ADOS‑2 Training Video Program and obtain sufficient practice before using the new module. Part 2 of the
Training Video Program provides training videos and a guidebook focused on the Toddler Module. Professionals who
are already trained in Modules 1 through 4 can purchase a training upgrade package for this purpose. No additional
training is necessary for Modules 1 through 4, as the basic administration and coding procedures have not changed.
(As noted earlier in this introduction, the videos included in Part 1 of the Training Video Program for Modules 1
through 4 have the same case examples that were included in the ADOS Training Video Program.)
Research users of the ADOS‑2 who are already trained in the ADOS will need to ensure their training is up to date for use
of the ADOS‑2. As noted in the previous section, links to relevant course information can be found on the WPS Web site.

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