This study tests the effects of affective and health-related outcome expectancies on physical exercise, assuming stronger direct and indirect (via intention) effects from affective outcome expectancy to physical exercise than from health-related outcome expectancy to exercise. Physical exercise and social cognitive variables were assessed at baseline, and 6- and 12-month follow-up in 335 older adults (60-95 years of age). Applying structural equation modelling, there was a direct effect from affective, but not from health-related outcome expectancy on intentions and behaviour. Also, the indirect effect from self-efficacy on physical exercise via affective outcome expectancy was significant, whereas the mediation via health-related outcome expectancy was not. These findings emphasise the relative importance of affective versus health-related outcome expectancies in predicting intentions and physical exercise in older adults and highlight the importance to separate these facets at a conceptual level to enhance both theory development and health promotion.