Research examining volunteer motivation and satisfaction has been criticised for the limited explanation of the cognitive and social processes that may underpin the proposed relationships among motivation, satisfaction, performance and retention (Costa, C.A., Chalip, L., Green, B.C., & Simes, C. (2006). Reconsidering the role of training in event volunteers’ satisfaction. Sport Management Review, 9(2), 165–182.; Cuskelly, G., Hoye, R., & Auld, C. (2006). Working with volunteers in sport. Theory and practice. London: Routledge.). Self-determination theory (SDT) (Deci, E.L., & Ryan, R.M. (1985). Intrinsic motivation and self-determination in human behavior. New York: Plenum.; Ryan, R.M., & Deci, E.L. (2000a) has proven useful in both for- and not-for-profit domains (e.g., Baard, P.P. (1994). A motivational basis for consulting with not-for-profit organizations: A study of church growth and participation. Consulting Psychology Journal, 46(3), 19–31.; Deci, E.L., Connell, J.P., & Ryan, R.M. (1989). Self-determination in a work organisation. Journal of Applied Psychology, 74(4), 580–590.; Hollembeak, J., & Amorose, A. J. (2005). Percevied coaching behaviors and college athletes’ intrinsic motivation: A test of self-determination theory. Journal of Applied Sport Psychology, 17(1), 20–36.) and appears particularly suited to understanding volunteer motivation. Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. American Psychologist, 55(1), 68–78.). Therefore the purpose of this study was to examine sport event volunteers’ motivation and experiences of the motivational climate at a large sport event using self-determination theory. The participants were volunteers at the NZ Master's Games held biannually in Dunedin, NZ. They participated in focus group interviews in which their experiences as volunteers at the event were discussed. In general, the findings support tenets of self-determination theory. Participants reported intrinsic motivation toward volunteering but also forms of extrinsic motivation toward some volunteer tasks. With regard to the motivational climate, volunteers experienced support for their autonomy, and felt that their competence and sense of relatedness were fostered. These findings suggest that SDT is a viable framework for examining volunteer motivation.