This qualitative case study uses a boundary crossing lens to explore pre-service teachers’ professional experience through their own perspectives and those of their mentor teachers. A constant comparative method was used to analyse multiple sources of data, including in-depth interviews, field observations, feedback sessions, and reflection meetings. Data analysis revealed three major themes and nine subthemes. These themes illustrated the way the pre-service teachers experienced boundary crossing throughout the professional experience, including (1) navigating collaborative and hierarchical relationships, (2) integrating converging and diverging epistemologies, and (3) engaging in identity work. The study details the subthemes by giving voice to converging and opposing perspectives and reveals the complexities inherent in boundary crossing. Implications for leveraging the professional learning of pre-service teachers echo previous studies and herald the need for considering multiplicity and hybridity in any bridge-construction endeavours across universities, schools and the spaces in between.