Research is an integral part of the UCL-led Early Career Framework (ECF) programme. The purpose of this research is to fill an important evidence gap on the impact of related programme-level, school-level, and system-level factors on the professional capabilities, wellbeing, and retention decisions of early career teachers (ECTs) and their mentors over time. This mixed methods research will provide robust evidence to understand: (1) Who the intended leavers, movers and stayers are over time; and (2) The extent to which and how their experiences on ECF programmes have influenced their professional dispositions and qualities, how effective they perceive themselves as teachers, and why they intend to leave, move (schools), or stay (in teaching). This report documents emerging findings from the initial ECT and mentor survey and is the first of a series of research reports and briefings that will be produced from this study.