In recent years volunteer labor emerges as one of the core components of sport service delivery, and plays a significant role in the overall success of recreational sport competitions. However, societal changes and emerging trends create a compelling need for leisure organizations to re-evaluate what is known about recruiting, coordinating and retaining volunteers. An extensive literature review revealed that, what we know today regarding the internal structure of motivation to volunteer in sports remains in an embryonic stage. In addition, questions regarding the demographic profile of sport volunteers or the primary motives that influence them to participate in volunteer activities have not been adequately addressed. The goal of this study was to provide organizers of recreational sport events the information needed to design, market, and implement successful volunteer recruitment programs. Specifically, this study focused on the following objectives: a) to investigate the demographics of volunteers for a marathon event; b) to examine the primary motives that influence the decision of sport volunteers to offer their services; and c) to explore the major dimensions of sport volunteerism. The event selected for the purposes of this study was the Country Music Marathon, a running event with international participation held in Nashville, Tennessee. From the 1602 volunteers that assisted in the organization of the marathon, 477 individuals accepted to review, complete and return the 40-item questionnaire validated in previous pilot studies. To assess the demographic characteristics of the sample, frequency analyses were conducted for all demographic factors. The results revealed that (a) 66% of the volunteers were females; (b) the highest proportion of respondents were between 25 and 34 years old (27%); (c) 31% of the volunteers had an annual income over $75,000; and (d) the overwhelming majority of respondents (92%) were Caucasian. In order to identify and interpret the motivational factors that influence volunteers to offer their services to a recreational sport event, the sample was divided in two sub-samples, Sx (n=238) and Sz (n=239). An exploratory factor analysis using a principal-component extraction technique was conducted for the Sx sample. The results suggested the existence of five motivational factors that were identified as material, social/leisure, egoistic, purposive and external influences. A confirmatory factor analytic procedure followed using the Sz sample, and confirmed the goodness-of-fit of the proposed motivational model. Additional research should be conducted with consideration to the size, location, purpose, and composition of volunteer labor.