This study examined propositions stemming from self-determination theory (Deci & Ryan, 1985), which contends that motivational consequences and positive outcomes are predicted by the needs for competence, relatedness, and autonomy. Participants completed the Psychological Need Satisfaction in Exercise (Wilson, Rogers, Rodgers, & Wild, 2006) scale and had their gym access activity monitored for six weeks. Regression analyses revealed that only competence emerged as a statistically significant predictor of exercise participation, and that this prediction was true for women only (p = .04). These findings suggest that exercise and health professionals must take care to ensure that this need is met, particularly in their female clients who may be impacted by traditional gender roles in sport contexts.