Outcome expectations have received little study in physical activity (PA) research. This study examined whether initial outcome expectations and their achievement at 6 months (i.e. outcome realizations) predicted subsequent PA participation (7-12 months) in 118 older women. Initial outcome expectations were not associated with PA participation. Outcome realizations at 6 months, however, predicted subsequent PA participation (p < .05). Women with high expectations but low attainment had the lowest subsequent participation rates. Women with high attainment, regardless of expectations, had the highest rates. Findings replicate and extend an earlier study and argue for a more dynamic conceptualization of outcome expectations.