The article explores the integration of Acceptance and Commitment Training (ACTr) into the field of Applied Behavior Analysis (ABA) to address complex behaviors, particularly those influenced by private events like thoughts and feelings. Key Concepts: Rationale for Considering Thoughts as Behavior: ABA traditionally focuses on observable behavior. However, this article argues that private events like thoughts should also be considered as behaviors susceptible to environmental influences and modification. Relational Frame Theory (RFT) and Private Events: RFT provides a theoretical framework for understanding how language and cognition, including thoughts and feelings, can influence behavior through relational framing and the transformation of stimulus function. ACTr in ABA: ACTr is a behavior analytic approach focusing on increasing psychological flexibility - the ability to be fully present and choose behavior based on values, even in the presence of difficult thoughts or feelings. It uses the six core processes of ACT (acceptance, defusion, self-as-context, present-moment awareness, values, and committed action) to analyze and intervene on complex behavior. By incorporating ACTr, behavior analysts can address behaviors that may not respond well to traditional direct contingency management. ACTr and Functional Assessment: The article emphasizes the importance of expanding functional assessment to consider the influence of covert verbal