In this dissertation, I develop an ethnographic case study of volunteering at an American zoological park, to address the more general issue of how status ambiguity and marginality affect role performance in organizations. Arguing that within the structure of modern, formal organizations, the status of volunteer is distinctively ambiguous and marginal, I contribute to previous research in volunteering by examining the effects of ambiguity and marginality on social interaction and the role experience in this setting. Rather than depicting volunteering as a predominantly free, individually-directed activity, the findings of this study suggest that volunteers' behavior is also shaped by the need to validate their marginal role identity. Since, unlike employees, volunteers depend predominantly on recognition to confirm their belonging in an organization, assuring the adequacy of recognition becomes a deliberate focus of volunteers' attention, alongside the substantive tasks that comprise their role. From 1997 to 1999 I conducted participant observation and interviews with volunteers and employees of Zoo Atlanta, in the state of Georgia. The volunteer program of this organization employed a relatively large number of volunteers, mostly in jobs that do not demand a great investment of time or holding special skills, and which involve interacting with visitors as representatives of the zoo. The study finds that volunteers' experience is variously shaped by (1) the extent of one's social involvement in the setting, which I characterized as "core" and "peripheral" social locations, and (2) the co-presence of different volunteer task roles, which are accorded different levels of informal prestige by participants. Generally, the findings suggest that the more centrally-involved in the program volunteers are, the more likely they are to take paid staff as their relevant reference group, and so the more they experience status marginality as a problem. The need to alleviate the ambiguity and marginality core volunteers sometimes feel is variously expressed in efforts to demonstrate their commitment, receive adequate recognition, and establish a sense of membership identity within the organization.