These answers draw in part from “Third Wave Applied Behavior Analysis: Evolving Our Science and Practice on a Foundation of Human Dignity” by Jonathan Tarbox, PhD., BCBA-D (BehaviorLive), and extend it with peer-reviewed research from our library of 27,900+ ABA research articles. Clinical framing, BACB ethics code references, and cross-links below are synthesized by Behaviorist Book Club.
View the original presentation →Third wave ABA refers to the current evolution within applied behavior analysis that expands the field's concerns beyond behavior change alone to include the dignity, autonomy, and wellbeing of the individuals served. Drawing a parallel from cognitive-behavioral therapy's third wave, which brought acceptance-based and values-oriented approaches, third wave ABA encompasses movements such as assent-based practice, compassionate care, trauma-informed ABA, neurodiversity-affirming approaches, and social justice in behavior analysis. These movements share common values centered on human dignity and represent a maturation of the field rather than a departure from its scientific foundations. The term describes a genuine evolution in how behavior analysts conceptualize their role, their relationship with clients, and the outcomes that define successful practice.
This is one of the central questions Tarbox addresses. Some third wave approaches have growing empirical support, while others are in earlier stages of conceptual development. Assent-based practice, for example, is grounded in research on social validity and client autonomy. ACT, which influences many third wave approaches, has a substantial evidence base. Neurodiversity-affirming practices are supported by qualitative research from the autistic community about the impacts of traditional approaches. However, some uses of third wave terminology may be more marketing than substance. The key is to evaluate each approach based on whether it is operationally defined, has empirical support, and is genuinely implemented in practice rather than accepting or rejecting them as a category.
Evaluate new approaches using several criteria. Does the approach have clear operational definitions for its core concepts? Is there empirical support, even if preliminary? Does it address a genuine gap in current practice? Is the approach grounded in behavioral principles, even if it introduces new terminology? Does the person or organization promoting it demonstrate genuine implementation in their own practice? Marketing schemes tend to use appealing language without operational definitions, claim transformation without demonstrating substance, and emphasize branding over practice change. Genuine advances may use new language but define it clearly, connect it to behavioral principles, and demonstrate how it changes what practitioners actually do with clients.
No. Neurodiversity-affirming ABA does not mean accepting all behavior without intervention. It means critically examining which behaviors we target and why. Behaviors that pose safety risks, cause the individual distress, or significantly limit the individual's functioning and opportunities remain appropriate targets for intervention. What neurodiversity-affirming practice challenges is targeting behaviors simply because they deviate from neurotypical norms, such as stimming that is not harmful, atypical social interaction patterns that work for the individual, or communication styles that differ from the majority. The key question is: whose wellbeing does this intervention serve? If the answer is primarily the comfort of others rather than the individual themselves, the goal warrants reconsideration.
Assent-based practice with individuals who have limited verbal communication relies on identifying and responding to behavioral indicators of assent and withdrawal. These indicators may include approach versus avoidance behavior, facial expressions, body tension, vocalizations, and engagement versus disengagement with activities. Clinicians should develop individualized assent profiles for each client that identify the specific behaviors that indicate willingness and unwillingness. When a client shows signs of distress or withdrawal, the practitioner should pause, modify the approach, or redirect to a preferred activity before reattempting. This is not the same as never proceeding with necessary interventions but rather ensuring that interventions are implemented in a way that respects the individual's ongoing behavioral communication.
The BACB Ethics Code (2022) both reflects and supports third wave approaches. Code 2.09 (Involving Clients and Stakeholders) supports assent-based practice and client-centered goal selection. Code 1.07 (Cultural Responsiveness and Diversity) supports neurodiversity-affirming and culturally responsive practice. Code 3.01 (Responsibility to Clients) supports the broader conception of client welfare that third wave approaches articulate. Code 2.01 (Providing Effective Treatment) requires treatment that is effective in ways that honor client dignity, not just effective in changing behavior. Practitioners who genuinely implement the ethics code are already engaging with many third wave principles, whether or not they use the associated terminology.
No, if implemented thoughtfully. Third wave approaches add dimensions of concern (dignity, autonomy, social validity) to existing behavioral rigor rather than replacing it. You still conduct functional assessments, use data to guide decisions, implement evidence-based procedures, and monitor outcomes. What changes is that you also attend to the quality of the therapeutic relationship, the social validity of goals and procedures, the client's ongoing assent, and the alignment of treatment with client values. This additional layer makes practice more comprehensive and more ethical without sacrificing the scientific foundation. The risk of reduced rigor arises only when practitioners adopt the language of third wave approaches without maintaining the methodological discipline that has always been central to ABA.
ABA's values have evolved through distinct periods. Early ABA prioritized demonstrating that behavioral principles could address socially significant problems, with emphasis on methodological rigor and replicability. The professionalization era added values of standardized training, credentialing, and accountability. The current period adds emphasis on client dignity, autonomy, cultural responsiveness, and the quality of the therapeutic experience alongside behavioral outcomes. Importantly, later values did not replace earlier ones but expanded the field's scope. Today's behavior analyst is expected to be methodologically rigorous, professionally accountable, and ethically attuned to the dignity and preferences of the individuals served. This expansion reflects the field's maturation and its responsiveness to feedback from the communities it serves.
Engage respectfully with their concerns while providing evidence and reasoned argument. Acknowledge that the rapid proliferation of new terminology can be disorienting and that skepticism is a healthy scientific instinct. Point to the BACB Ethics Code (2022) as an authoritative document that reflects many third wave values, making them professional standards rather than optional trends. Share specific examples of how third wave approaches have improved your practice or client outcomes. Distinguish between the substance of these approaches and any superficial marketing that may accompany them. Ultimately, colleagues are more likely to be persuaded by seeing the approaches in action and observing their impact on clients than by theoretical arguments alone.
As Tarbox emphasizes, the common thread across third wave movements is a commitment to human dignity. This manifests as respect for client autonomy (assent-based practice), recognition of neurological diversity as natural variation (neurodiversity-affirming approaches), attention to the emotional experience of clients and practitioners (compassionate care), acknowledgment of how trauma affects behavior (trauma-informed care), and concern for equitable access to services and fair treatment of diverse communities (social justice). These are not competing movements but different expressions of the same underlying value: that the people we serve are whole human beings whose dignity must be protected and promoted in every aspect of our practice. Understanding this common foundation helps practitioners see these approaches as complementary rather than contradictory.
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Third Wave Applied Behavior Analysis: Evolving Our Science and Practice on a Foundation of Human Dignity — Jonathan Tarbox · 1 BACB Ethics CEUs · $15
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All behavior-analytic intervention is individualized. The information on this page is for educational purposes and does not constitute clinical advice. Treatment decisions should be informed by the best available published research, individualized assessment, and obtained with the informed consent of the client or their legal guardian. Behavior analysts are responsible for practicing within the boundaries of their competence and adhering to the BACB Ethics Code for Behavior Analysts.