By innovatively applying positioning theory with reference to a framework of willingness, capability and power, this study explored how pre-service teachers' professional identities dynamically change through the negotiation of various positions. A qualitative approach was adopted using data from six Hong Kong pre-service teachers in a teacher education programme for teaching Chinese as a second language. Multiple data sources, including interviews, reflective journals, classroom observations and lesson plans, were collected over one year. Pre-service teachers were found to negotiate individual deliberated self-positionings before entering the education programme and forced self-positionings from significant others during the education programme in three key stages: pre-positioning, negotiated positioning and performed positioning. Three differentiated positioning trajectories were identified that were greatly influenced by the pre-service teachers' levels of willingness, capability and power.