In Behavioral Activation (BA) for depression (Martell, C. R., Addis, M. E., & Jacobson, N. S. (2001)), which has recently received empirical support in a large randomized trial, therapists pay close attention to the function of behavior and the role of aversive controlling stimuli and escape and avoidance behavior in depression. A key variable to measure in studies of BA is when and how clients become more activated over the course of treatment. This study sought to develop an initial set of items for the Behavioral Activation for Depression Scale (BADS), submit these items to an exploratory factor analysis in an initial administration (Study 1, N = 391), and submit the resulting scale to a confirmatory factor analysis in a second administration (Study 2, N = 319). Results indicated four factors (Activation, Avoidance/Rumination, Work/School Impairment, and Social Impairment) with good factor structure, internal consistency, and test-retest reliability. Evidence for construct and predictive validity is presented.