Little is known about the predictors of maintenance in organized exercise programmes. The aim of this study was to investigate the behavioral predictors of maintenance of exercise participation in older adults, using an integrated social psychological model. To this end, we carried out a prospective cohort study (n = 1,725; age 50 years or older) involving 10 different types of exercise programmes, with measurements at baseline and after 6 months. Predictors of intention to continue participating and the actual maintenance of exercise participation in the exercise programme were assessed using a step-wise logistic regression model. Significant odds ratios (ORs) predicting the intention to continue with the exercise programme were found for female sex, younger age, being married, being a non-smoker, being in paid employment, having a positive attitude towards exercise and having a high self-efficacy at baseline. Significant ORs predicting actual maintenance of exercise participation were short lapses, absence of lapses, high intention at baseline, high perceived quality of the programme, positive attitude at baseline and few risk situations at baseline. In order to promote maintenance of exercise participation for older adults, effort should be taken to prevent lapses, to help people cope with risk situations for lapses, to improve the attitude towards exercise participation and to improve the quality of the programme.