In 61 drug-free depressed patients, relationships were studied between observed behaviors and measures of common clinical concepts of activation. The behaviors were observed during a clinical interview and analyzed with ethological methods. Activation was assessed by means of self-ratings (Thayer, AD-ACL) and global judgement (Hamilton, retardation, agitation). Various aspects of patients' speaking and listening behaviors were recorded and analyzed, such as looking, head movements, yes-nodding and no-shaking, leg movements, gesturing, and body and object touching. A factor analysis was applied, enabling grouping of behaviors without using a priori concepts. Five factors reflected different aspects of a conversation: restlessness (leg and hand movements), speech, active listening (head movements and intensive body touching, during listening), speaking effort (looking, gesticulating, head movements, during speaking), and eagerness (yes-nodding and no-shaking). Significant positive relationships were found between the speech factor, the speaking effort factor and the restlessness factor on the one hand, and activation on the other. The eagerness factor was related negatively with activation. The results give insight into the organization of behavior during an interview, and show how this is related to clinical concepts of activation.