1N4Abstract For Canadian and United States Masters swimmers we examined how career contingencies (age, sex, familial status, and stage of swimming experience) were linked to benefits derived (personal and social rewards -importance of reasons for participation) from their pursuit of this serious leisure sport career. From questionnaire data on convenience samples of Masters swimmers, Canadian (337) and U.S. (363), we identified reasons for adult participation in competitive swimming, measured the relative importance of reasons, and ascertained whether the relative importance of reasons varied by age, sex, familial roles, or swimming experience. A factor analysis of 25 reason statements extracted six factors (sociability, achievement, fitness, skill development, enjoyment, and tension release). A series of regression models specified which career contingency variables were linked to each reason and whether differences existed across samples. In sum, Canadian and U.S. swimmers generally endorsed similar reasons for participation. U.S. swimmers assigned greater importance than Canadians to achievement, fitness, and tension release. For the career contingencies: fitness, sociability, and enjoyment were important to females; all ages viewed fitness, achievement, skill development and sociability as important; and stage of swimming experience was linked to relative importance assigned to skill development and achievement.Although the phenomenon is much older, the term &dquo;serious leisure&dquo; only dates from the past decade when Stebbins (1982) sketched the rudiments of the idea in a conceptual statement. Since then a standard short-hand definition has evolved: serious leisure is &dquo;the systematic pursuit of an amateur, hobbyist, or volunteer activity that is sufficiently substantial and interesting for a participant to find a career there in acquisition and expression of its special skills and knowledge&dquo; * We gratefully acknowledge the assistance of Robert A. Stebbins, Richard A. Wanner, and Michael Benson for their constructive comments in manuscript preparation. We also acknowledge the assistance Donald R. Ploch on the statistics.