Declining membership is a concerning, yet poorly understood issue affecting professional associations across many disciplines (Bauman, 2008). The discipline of rehabilitation counseling is experiencing membership decline even as the number of certified rehabilitation counselors continues to increase (Leahy, 2009). Little empirical research exists on professional association membership and motivations for membership. The purpose of this study was to explore factors that might influence professional association membership in rehabilitation counseling professional associations and to test theoretical hypotheses about membership; pursuit of this purpose was guided primarily by tenets of social exchange and social identity theories. Social exchange theory is the theory most commonly associated with professional association membership. However, challenges in the application of exchange theory to influence membership decisions are many during periods of declining membership. Efforts to increase overall value can become strained by the loss of revenue resulting from a reduction in membership dollars. Social identity theory is offered, in addition to social exchange theory, as an explanation for membership decisions. In social identity theory, the influence of group membership on self-identity becomes primary (Tajfel, 1981). In line with social identity theory, professional identity was defined for this study as a special form of social identity in which a person defines him or herself by membership in an occupation believed to approximate that of a profession. A sample of 1,257 professionals closely connected to the discipline of rehabilitation counseling was obtained for this study from the databases of CRCC, ARCA, NRCA, and RCEA. This sample included 450 participants who currently held membership in at least one rehabilitation counseling professional association, 324 participants who formerly held membership in at least one rehabilitation counseling professional association, and 483 participants who had never held membership in a rehabilitation counseling professional association. Research findings expand on the work of previous research in the area of professional association membership and membership commitment. As hypothesized, results showed professional identity salience was positively related with current membership status and levels of affective and normative commitment. Also hypothesized, perceived value of membership was positively related with current membership status. In contrast, the hypothesis that private benefits would act as the only type of benefits predicting current membership was not supported. Results suggest graduate programs and employing organizations also play an important role in encouraging membership. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]