Behavioral science theorists who study pain have advocated the development of measures designed to assess aspects of behavior. Recently, Diller , Fordyce , Jacobs, and Brown developed a 64-item self-report activity measure. Assessment of functional impairment associated with pain is a potentially appropriate application for the Activity Pattern Indicators (API). The API provides a description of actual functioning; frequency of behavior is the unit of measurement. Currently, no agreed upon scoring protocol is available for this measure. We propose to design, in accordance with measurement theory, a psychometrically sound yet practical scoring protocol. The API data presented allow an acceptable degree of reliability and sensitivity to group differences. Results of the present study support continued psychometric exploration of: the current scoring protocol, alternative scoring protocols, and the Activity Pattern Indicators.