The relationship between children's activity level and adjustment has been based on a one-dimensional conceptualization of activity level and warrants re-examination. Current questionnaires conflate amount of physical movement with its appropriateness to the context, making it impossible to tell which aspect of activity level accounts for its links with adjustment. This investigation, using a Structured Temperament Interview (STI), separated two activity level dimensions, extent of physical movement (Vigor) and its attunement to the context (Modulation). In two samples, questionnaire measures of activity level correlated positively with Vigor and negatively with Modulation, indicating that high Activity scores reflect a combination of high Vigor and low Modulation. Modulation, but not Vigor, correlated with adjustment as indexed by classification with emotional disability in the school system and by scores on the Behavioral Assessment System for Children. After removal of variance contributed by Modulation, significant correlations were attenuated between adjustment and activity level measured with the Dimensions of Temperament Survey-Revised. (Contains 7 tables.)