Sport participants have an economic value up to four times higher than that of sport spectators in the United States according to Kim, Smith, and James (2010). One participatory sport that has experienced tremendous growth in participation numbers worldwide since the mid-1990s is road racing. Road race event organizers currently face increased competition with each other to attract participants. Therefore the purpose of the study was to better understand the core determinants (or factors) believed to influence the behavior of road race participation. Advancing our understanding will assist sport managers in differentiating their events from competitors and increasing participation numbers in an increasingly crowded marketplace. Using Bandura’s Social Cognitive Theory (SCT), the authors qualitatively examined participant narratives about their participation in the BolderBOULDER 10K, an annual road race hosted in Boulder, Colorado. Four major themes emerged from the narratives: family, health, the event experience, and empowerment. While some themes were consistent with previous findings, family and the event experience differed from previous sport marketing findings. Furthermore, these findings suggested that a participatory sporting event organizer’s ability to understand what drives participants’ behavior to run the race year after year may be key for event differentiation. Additional analysis relating to the SCT is presented, and implications and future research ideas are provided.