We furnish a theoretical framework for explaining that portion of formal variability in artifacts attributable to the behavior of the artisan. Major causal factors are the artisan's knowledge and experience, extent of feedback on performance in activities along the artifact's behavioral chain, situational factors in behavioral chain activities, technological constraints, and social processes of conflict and negotiation. In identifying the causal factors at work in a specific case, the investigator must focus analytically on activities-that is, on people-people, people-artifact, and artifact-artifact interactions-and on the performance characteristics relevant to each. Application of this behavioral framework allows abandonment of many cherished but unhelpful concepts, including style and function. Ceramic artifacts, the low-fired, clay cooking pot in particular, are employed for illustrative purposes.