Education policy in England requires student teachers to demonstrate effective teaching of early reading, including systematic synthetic phonics, in order to qualify. However, central monitoring of student teacher satisfaction in initial teacher education (ITE) indicates that some students feel inadequately prepared to teach reading as they enter the profession. Furthermore, recent policy changes to ITE on postgraduate routes have increased time in schools and reduced time in the university. In this challenging climate, little is known about how student teachers develop knowledge, understanding and practice for teaching early reading whilst moving between the different learning environments of schools and university and how they adapt to the first term as newly qualified teachers (NQTs). This research used a longitudinal, collective case study design involving seven lower primary (3–7 years) postgraduate certificate in education (PGCE) students enrolled at one university in the East Midlands of England. Semi-structured interviews, classroom observations and documentary analysis with the students and their teacher mentors were used to gather data from entry onto the course to the participants’ first term as qualified teachers. A conceptual and analytical framework, developed using activity theory, provided an original and innovative way of examining the complex interplay of influential factors within and between schools and the university. Conceptualising ITE as the product of multiple activity systems identified important tensions between the goals and expectations of schools and the university and the potentially unexamined impact of institutional responses to policy on becoming a teacher of early reading. The findings indicate that student teacher progress was constrained or facilitated by key elements of the activity systems involved which highlight implications for university organisation, mentoring and whole school participation. Recommendations from the research include a new continuum of teacher development and an ideal activity system for ITE and induction for early reading.