Transition into formal school is an important milestone for young children and their families. Teachers in both schools and early childhood settings play a significant role in supporting children and their families through this process. They are charged with developing collaborative partnerships to ensure a continuity of learning for children between these two settings. In 2017 teachers from both early childhood and school age settings across Victoria, Australia, were invited to participate in joint professional learning to build understanding of effective transition to school processes, as well as develop professional cross sector understanding. Prior to registering for this professional learning workshop, participants were asked to identify what they believed the most significant challenge for transition to school to be. Around 5000 teachers from across both primary schools and early childhood settings responded to this question. The responses were analysed using a qualitative content analysis to code emerging themes. Findings show that prior to attending the formal professional learning workshop, the majority of both early childhood and primary school teachers raised school readiness as a concern. However, further analysis identified that teachers had a variety of perceptions as to what this entailed. In many instances the early childhood teachers’ perceptions of what the primary teachers expected did not correspond with what the primary schools teachers were raising. This study highlights the importance of shared cross-sector conversations during transition to build shared professional understanding.