[영문]Little is known about potential longitudinal relationships between participation in social, physical, and intellectual activities and later cognitive performance. Data from the Victoria Longitudinal Study (n = 530) were used to test whether baseline and change in lifestyle engagement were related to corresponding indicators of cognitive speed (measured by mean-level and intraindividual variability). Regressions based on random effects model estimates showed that cross-sectional activity participation predicted corresponding values of both mean-level and intraindividual variability, but few longitudinal relationships were significant. Overall, a higher frequency of participation in cognitively complex activities was related to faster response times and lower intraindividual variability. Findings suggest that activity level at one point in time may be a more important predictor of cognition than an individual's changes in activity level.