• health-enhancing physical activity;
  • self-determination theory;
  • well-being

Background: The association between health-enhancing physical activity (HEPA) and well-being was investigated across a cross-sectional (Study 1; N = 243) and a longitudinal, two-wave (Study 2; N = 198) design. Study 2 further examined the role played by fulfilling basic psychological needs in terms of understanding the mechanisms via which HEPA is associated with well-being. Methods: Women enrolled in undergraduate courses were surveyed. Results: In general, greater HEPA was associated with greater well-being (Study 1; rs ranged from .03 to .25). Change score analyses revealed that increased HEPA positively predicted well-being (Study 2; R2adj = 0.03 to 0.15) with psychological need fulfilment underpinning this relationship. Conclusions: Collectively these findings indicate that increased engagement in health-enhancing physical activity represents one factor associated with greater well-being. Continued investigation of basic psychological need fulfilment as one mechanism underpinning the HEPA–well-being relationship appears justified.