This study reports on age-group differences in leisure-time sport and physical activity involvement among a large sample of Canadians interviewed at 2 points during the 1980s. Comparisons are made for 5 age cohorts, for men and women, and without and with multivariate controls. The results contradict the usual finding of an inverse relationship between age and level of physical activity. On measures of (a) activity necessary to produce health benefits and (b) energy expenditure. Canadians over 65 were as active as, or more active than, their younger counterparts, and their activities did not decline over the 7 years between interviews. The extent of change varied by age and across women and men. Among women, increases in involvement were greatest in the middle-aged. Among men, the greatest increase was in the oldest age groups. For both genders, the youngest age cohort showed the smallest change over time, and there was evidence of slight declines in activity levels among young men.