We report on a survey of 1717 students at two different points of their secondary school education. This survey is designed to discover their reasoning about scientific and religious accounts of the origins of the universe and life. The study was motivated by a concern, based on previous research, that factors such as the compartmentalised curriculum may limit students' progression in interdisciplinary reasoning and their capacities to appreciate why science and religion are not necessarily incompatible. To investigate these matters, we gathered data in seven secondary schools in England. The findings indicated that a significant proportion of students are working with a poor understanding of the limits of science and of the range of scholarly positions on the nature of religious explanation. The implications of the results for educational theory and practice are discussed.