Learning how to plan is recognised as a key skill that beginning teachers have to develop but there has been little research examining "how" they may actually learn to plan. This paper, based on the analysis of 10 post-lesson interviews with 17 secondary school teachers across three years (the PGCE year and the first two years in teaching) focuses on: what these beginning teachers learned about planning; the nature of that planning; and the development of their awareness as to what planning could and could not achieve. The findings demonstrate that learning how to plan is a feature of beginning teachers' learning well beyond the PGCE year, indicating that it is through planning that teachers are able to learn about teaching and through teaching that they are able to learn about planning. We discuss the implications for teacher educators and others involved in the professional learning of beginning teachers. (Contains 3 notes and 3 tables.)