School partnerships to manage transition between primary and secondary settings are well developed. However, studies show that some aspects of transition in Modern Languages leave much to be desired, as mentioned in a recently published report on KS3 provision ([Office for Standards in Education. 2015. "KS3: The Wasted Years?" https://www.gov.uk/government/publications/key-stage-3-the-wasted-years]), even if the importance of a seamless continuum to manage change effectively is clearly emphasised by policy makers and advocated by research. Addressing transition issues entails considering a myriad of parameters. Government policy and 'good practice' cannot be implemented without consideration for school characteristics and teachers' professional circumstances and areas of expertise. The focus of this article lies on uncovering opportunities for professional learning offered by cross-phase collaboration between primary and secondary students on initial teacher training programmes. Students took part in a small-scale project and they were challenged to work collaboratively and to co-plan and co-teach a lesson to primary school pupils. The project investigated outcomes of collaboration for professional learning. Data, both quantitative and qualitative, were collected through questionnaires. Results showed the impact of collaboration on students' self-awareness and awareness of their colleagues' areas of developing expertise as well as implications for professional practice.