While the running community has experienced tremendous growth over the past several decades, increased competition and plateauing participation rates have made effective race marketing an imperative. This study examined the repeat registration behavior of running event participants through the lens of Ehrenberg’s (1988) repeat-buying theory. We used Customer-Base Analysis on combinations of observed frequency and recency patterns in runner registrations over a seven-year period. Based upon registration data (N = 26,625), we found that runners with the highest probability of registering for future races have run the race within the previous two years. Results from the current study offer insights about repeat purchase behavior of race participants that can help determine allocation of scarce marketing dollars.