Aim: The increasing importance of integrative practice highlights the need to explore how trainees develop their theoretical stance. This investigation explored the experiences of trainees to elaborate a model of how they developed their personal theories of practice. Method: Seventeen Masters level trainee counsellors kept weekly journals recording how they developed a working theory of practice. Grounded theory analysis of the journals was used to develop a model of the process. Findings: The resulting Process Model of Tentative Identifications illustrates how a personal theory developed through trainees' tentative identifications with theories of practice, and how factors such as reading, personal philosophy, practice, and supervision interact to produce the identifications. A diagram of the model highlights the relationships among a variety of personal and professional factors that ranged from highly abstract to concrete and practice‐based. Discussion: The model is consistent with several factors identified in previous research and highlights how trainees develop working theories of practice.