Activity pacing is frequently included among the strategies provided to individuals with chronic pain to manage pain and improve functioning. Individuals with chronic pain may, however, limit their use of activity pacing because they perceive significant obstacles to its use. This study describes the development of a measure to assess obstacles to activity pacing and examines the relationship of this measure to activity patterns and functioning. A sample of 637 individuals with chronic pain completed items describing potential obstacles to activity pacing as part of their pretreatment assessment. Item analyses were used to construct a 14-item measure of obstacles to activity pacing. A subset of these individuals completed the measure again after completion of a group treatment program. The resulting measure demonstrated excellent internal consistency and was minimally affected by social desirability. Correlations with measures of activity and psychosocial functioning provided initial construct validity for the measure. Sex differences were found with women initially identifying more obstacles to activity pacing. Fewer obstacles were identified by both men and women after treatment, and these changes were related to modest changes in activity patterns and functioning. The present results identify a number of obstacles that may limit the use of activity pacing by individuals with chronic pain. Treatment may result in a decrease in the number of obstacles identified, and this change is related to changes in the individual's activity pattern and psychosocial functioning.