This article reports on the first stage of a study by a group of researchers involved or interested in principal (headship) preparation in Western Australia, Canada, England, Jamaica, Mexico, Scotland, South Africa, Turkey and the United States. The study, known as the International Study of Principal Preparation (ISPP), discusses the background to the current policies in principal preparation, and examines the standards-led approach to principal preparation. This paper focuses on England and Scotland for comparative purposes, and asks how much we know about the effectiveness of current principal preparation.