The role of functional assessment in third wave behavioral interventions: foundations and future directions for a fourth wave

• Functional assessment is at the core of behavioral interventions.
• Some assessment approaches to contemporary behavior therapies have lost functional assessment in treatment planning.
• There is an advantage to focusing on the client and functional assessment.
• A fourth wave of behavior therapy may emphasize functional assessment.
• This new wave allows therapists to select strategies to treat each client.

Functional assessment remains an essential aspect of behavior therapy and is the foundation of many contemporary behavioral interventions. In this paper, we articulate the role of functional analysis in third wave behavior therapies and assessment approaches that attempt to accomplish functional assessment in clinical practice. In addition, the compromises in functional assessment and associated costs to the integrity of behavior therapy and functional approaches are discussed with respect to a focus on randomized control trials (RCTs) and diagnostic categories. We propose that a fourth wave of behavior therapy is possible to anticipate, one that focuses on functional assessment and utilizes aspects of available contemporary behavior therapies as treatment strategies integrated into a coherent Contextual Behavioral Intervention.