Ultramarathon running, competing in distances beyond the 26.2 mile marathon, is one of the fastest growing segments of endurance competition. The sport has more than tripled in entrant size over the past 12 years and now attracts over 26,000 athletes on an annual basis. However, there is a limited understanding of what motivates individuals to pursue such a taxing physical and emotional activity. This study explored the dimensions of the Zaichkowsky Personal Involvement Inventory (PII) and the Laurent and Kapferer Consumer Involvement Profile (CIP) as predictors of ultramarathon runners' intention to participate, behavioral participation, and perceived skill level. Multiple regressions indicated that the cognitive and affective facets of the PII scale were significant in predicting the behavior and that the cognitive facet of the PII scale was a unique significant predictor of the perceived skill. In addition, it was found that the CIP affective dimensions of "pleasure" and "sign value" were unique significant predictors of the intention to participate. (Contains 2 figures and 3 tables.)