This article presents the results of a study of the impact of three programmes of the National College for School Leadership (NCSL), namely Leading from the Middle, the National Professional Qualification for Headship and the Leadership Programme for Serving Headteachers. All three programmes embody a blended learning approach that includes an in-school component. This article focuses on factors within the programmes that influence learning from the in-school components. It focuses particularly on factors relating to individual participants and to the school contexts within which they work. The article relates the findings to previous literature on work-based learning and suggests a broader model of the factors that influence the outcomes of leadership development programmes. (Contains 6 tables, 1 figure and 3 notes.)