Inadequate physical activity remains a significant problem for older adults in the U.S. Because many who initiate physical activity have difficulty sustaining their efforts, we developed a maintenance intervention targeting those who had recently increased their PA to a minimum of two days a week of at least moderate intensity PA, for at least 30 minutes a day. We have recently completed an RCT evaluating the efficacy of a 24-month physical activity maintenance program (Keep Active Minnesota) in 1,049 adults age 50-70 recruited from the membership of one managed care organization. Following baseline assessment, study participants were randomly assigned to either a 24 month phone- and mail-based KAM intervention (KAM; n=523), or a usual care condition (UC; n=526). Physical activity was assessed at baseline, 6mo, 12mo, and 24mo follow-ups in terms of kcal/wk expenditure in total activities, and moderate/vigorous activities, based on self-report data using the CHAMPS questionnaire. We have previously documented baseline similarities between groups and a significant benefit of the intervention at 6 month follow up. We now report a sustained, significant benefit of the intervention at 12 and 24 months. Mean change in total kcal/wk expenditure at 12 months was positive for KAM participants, but negative for UC participants (time x treatment, p<.01). Mean change in MVPA kcal/wk expenditure at 12 months was also positive for KAM participants, and negative for UC participants (p<.001). Similarly, mean change in total kcal/wk expenditure at 24 months was positive for KAM participants, but negative for UC participants (p<.001). Finally, mean change in kcal/wk expenditure in MVPA at 24 months was also positive for KAM participants, but negative for UC participants (p<.001). This phone- and mail-based PA maintenance intervention was effective at maintaining PA in both the short-term (6 months) and longer-term (12 and 24 months). The intervention model is simple, relatively inexpensive and widely disseminable to a variety of community care settings.