Postgraduate student teachers' conceptions of sustainable development were elicited using a questionnaire completed by the entire cohort of geography (N = 21) and science (N = 40) students starting the University of Oxford Post Graduate Certificate in Education (PGCE) secondary course. Responses were analysed in three ways: (i) development of categories to capture features of sustainable development; (ii) scrutiny of individual responses for the presence or absence of key features (specifically environmental, economic and social factors); and (iii) in contrast to these grounded approaches, examination of the responses in light of a pre-specified framework. Notable findings were: (i) the large numbers recognizing the centrality of environmental (87%), economic (69%) and social (49%) factors--about a third highlighted all three factors (the geographers significantly more so than the scientists), while a further third mentioned two of them; (ii) when compared with the pre-specified framework, the aspects of sustainable development largely missing were to do with preservation of diversity, and with uncertainty and precaution in action; (iii) only one response contained an aesthetic element; and (iv) when comparing education for sustainable development with environmental education, the most frequent view identified the former as broader. The findings are related to contemporary literature in the field and some implications for PGCE learning are considered.