The purpose of this study was to examine select psychometric properties of the Behavioral Regulation in Exercise Questionnaire (BREQ; Mullen, Markland, & Ingledew, 1997). To accomplish this aim, data were gathered in 2 phases to evaluate the BREQ's factorial composition and structure and the relation between the BREQ, need satisfaction, exercise behavior, and relevant motivational constructs. Participants completed measures assessing psychological need satisfaction, optimism, perceived behavioral control, exercise behavior, and the BREQ. Phase 1 results supported the original 4-factor measurement model and a simplex model of structural relations between latent BREQ constructs suggested within self-determination theory (Deci & Ryan, 1985), and results supported the positive relations between more self-determined motives and greater psychological need satisfaction and frequent exercise behavior. Phase 2 results provided further construct validity evidence for the BREQ by linking subscale scores with greater perceived behavioral control in a manner consistent with theory (Deci & Ryan, 1985). Collectively, these results further support the construct validity of the BREQ and lend credence to the notion of measuring exercise motivation from a multidimensional perspective using self-determination theory as a guiding framework in the exercise domain.