Inspired by Steenbeek and van Geert’s (2015) proposal that teachers need to become process researchers of their own development, and making use of methods of retroduction, the innovation we present comes in the form of a model that provides preservice language teachers with the knowledge and tools needed to map the dynamics of identity development during practicum periods. We provide an outline of the model and describe how we used it mentoring a group of preservice teachers. When mentors take on the role of complexity coaches and offer insights into complexity principles such as nonlinearity and the interrelationship of timescales, students have opportunities to investigate shifts in their emerging teacher identities, and to identify the signature dynamics of their identity systems. Taking on the role of a process researcher, preservice teachers can gain important self-insights and become able to identify and make sense of identity transformations. By facilitating such insights and providing opportunities for ‘in-the-moment identity management’, the model can play an important role in the process of developing a coherent professional identity.