This research describes the development and validation of a measure designed to assess feeling states that occur in conjunction with acute bouts of physical activity-the Exercise-Induced Feeling Inventory (EFI). The EFI consists of 12 items that capture four distinct feeling states: revitalization, tranquility, positive engagement, and physical exhaustion. The multidimensional structure of the EFI is supported by confirmatory factor analysis. The subscales have good internal consistency, share expected variance with related constructs, are sensitive to exercise interventions, and appear responsive to the different social contexts in which activity may occur. After describing the psychometric properties of the EFT, several directions for theory-based research are proposed.