The Behavioral Activation for Depression Scale (BADS) was developed to measure core concepts of behavioural activation for depression. A number of studies, mostly based on analogue samples, have provided initial support for the BADS. In the present study, we examined the psychometric properties of the German version of the scale more broadly, including change sensitivity and clinical treatment data. A mixed sample of students (N = 312) and depressed outpatients in partial remission undergoing cognitive‐behavioural group treatment for depressive rumination (N = 59) was examined. To analyze construct validity, a set of theoretically relevant constructs such as perseverative thinking, distraction and mindfulness was also assessed. Results indicated good psychometric properties, additional evidence for construct validity of the total scale and subscales, and adequate fit of the data to the original factor structure. Furthermore, the BADS proved to be sensitive to changes in participants undergoing treatment for depression. Copyright © 2015 John Wiley & Sons, Ltd. Key Practitioner Message Behavioural activation (BA) is an effective treatment for patients suffering from unipolar depression. The Behavioral Activation for Depression Scale (BADS) can be used to measure core elements of the BA treatment rationale. It is useful to track changes in activation within treatment. The BADS is available in different languages and has shown to possess good psychometric properties.