After a randomized controlled trial showing that improvement on some aspects of cognitive function was related to adherence to an exercise program, determinants of adherence and maintenance were further studied. Older adults with mild cognitive impairment were contacted 6 mo after the end of exercise programs for a telephone interview addressing patterns of adherence and determinants of maintenance. Mean adherence during the trial was 53%. About one third of participants had lapses during the trial but completed, one third had no lapses, and one third dropped out or never started. Practical barriers (time, location) were related to not starting and functional limitations to dropout. After the trial 25% of participants continued the programs, 14% reported intention to continue, and 61% quit. Maintenance was determined by fewer health complaints, higher satisfaction with the programs, and better adherence during the programs. Although maintenance was low, this study identified several reasons and barriers to adherence and maintenance that could be addressed.