This paper explores the development of professional identity as a relationship between professional and personal aspects of life. The focus is on student and novice professional psychologists' and political scientists' processes of professional identity formation in their transition from higher education to working life. Drawing on Wenger's theory of nexus of multimembership (1998), the findings indicate that professional identity is a dynamic relationship between different life spheres rather than an isolated phenomenon only taking place at the university or in the work context. The analysis yielded three different forms of professional identity, non-differentiated identity, compartmentalised identity and integrated identity, which exemplify different negotiated relationships between professional, personal and private life spheres. The findings show that these three forms of professional identities are sequential, from an individual focus to more relational and integrated ways of reasoning about one's profession. It is through the negotiations between personal and socially derived imperatives that identity formation progresses throughout working lives.