Theoretical and political perspectives on the nature of professionalism in teaching are abundant, but little is known about the views of teachers themselves. We asked primary and secondary school teachers in England what teacher professionalism means to them. We explored what teachers think about professionalism, on what dimensions their thinking varies, and how much it varies. We researched how successful the government had already been, and how successful it would be in the future, in changing teachers' conceptions of professionalism. Two large-scale national surveys were conducted, with a longitudinal element. We found that teachers' thinking about their professionalism may be construed as consisting of an inner core of strong, shared beliefs and commitments; an intermediate set of coherent but contested components of professionalism; and an outer layer of disparate elements which are generally highly disputed and which remain unintegrated into broader ways of thinking. (Contains 2 notes and 8 tables.)