Today, military public relations, or military public affairs (Levenshus, 2013), is drawing attention for the lessons it might have to offer to organizations more broadly. Yet, military public affairs has been neglected within the public relations scholarly field (Toledano, 2010). In the present study, I applied the “social identity approach” (Hornsey, 2008, pp. 204-205) as my conceptual framework to explore the development of military public affairs professional identity through socialization of public affairs managers in joint entry-level military public affairs training. Along with professional identity and organizational socialization, I explored the development and practice of collaboration as a public affairs competency. To complete the study, I conducted semi-structured interviews (27 initial interviews, three follow-up interviews) with 27 students, practitioners (i.e., former students), instructors, and administrators of the U.S. Defense Department’s entry-level Public Affairs Qualification Course. Findings supported the scholarly understanding that public relations practice is a boundary spanning function, with internal boundary spanning an important aspect of the public affairs manager’s work (Neill, 2014). Findings helped to extend understanding of organizational socialization by suggesting that the public affairs manager, as a nonprototypical member of the organization, must be accepted by the commanding officer and other leaders, often representing combat arms fields, to achieve inclusion in the organization (Wenzel, Mummendey, & Waldzus, 2007). Findings further helped to broaden understanding of public relations collaboration by drawing attention to vital collaboration partners that have been obscured through their agglomeration in the concept of the “dominant coalition” (Grunig, 2006, p. 160). Findings suggested the new insight that public affairs managers are socialized for proactivity, an unexpected outcome given the priorities of military organizations as “high-reliability organizations” (Myers, 2005, p. 345). Additionally, findings suggested that ambiguity attends the public affairs function and that this ambiguity can constrain public affairs, but also create opportunities for collaboration, especially under conditions of contextual uncertainty (L. A. Grunig, 1992; Rast, Gaffney, Hogg, & Crisp, 2012). Findings additionally suggested that collaboration opportunities may increase for public affairs when those efforts are more visible to the organization and are seen to benefit it (Platow & van Knippenberg, 2001).