This paper examines data generated during the first year of the Becoming a Teacher (BaT) Project, a six-year (2003- 2009) longitudinal study of teachers' experiences of initial teacher training (ITT), induction and early professional development in England. The study is funded by the Department for Education and Skills (DfES), the General Teaching Council for England (GTCE) and the Teacher Training Agency (TTA), and is carried out by researchers at the University of Nottingham, the University of Leeds and MORI Social Research Institute. The research tracks student teachers / trainees entering the profession via a range of different routes into teaching (including undergraduate and postgraduate university-administered programmes, school- centred initial teacher training [SCITT] programmes, and the Graduate and Registered Teacher Programmes [GRTP]) over a period of five academic years. This paper explores issues relating to trainees' expectations and preconceptions about ITT, and their subsequent early experiences of ITT. Previous research has suggested that, like all learners, student teachers view and interpret new information and experiences through their existing network of concepts, experiences and beliefs (e.g. Richardson, 1997: Fosnot, 1996). Thus trainees' preconceptions about teaching and learning may impact on their experience of ITT (e.g. Feiman-Nemser et al, 1987; Korthagen et al, 2001). Sugrue (1996) has noted, for example, that trainees' prior beliefs can create barriers in their receptiveness to the different component parts of ITT programmes. These issues are further explored in the context of a large scale study of beginner teachers in England, which also seeks to examine the extent to which trainees' experiences differ across different ITT routes. Data were generated via a questionnaire survey, which was completed by 4,790 student teachers at the beginning of their final or only year of ITT, and via in-depth interviews with a sub-sample of 85 survey respondents. The survey and interviews sought to explore various issues associated with: (1) trainees' early experiences of ITT; (2) their prior expectations and preconceptions relating to ITT; and (3) their previous career histories. In this paper we report findings relating to: " trainees' expectations and preconceptions about ITT, including their perceptions of the potential utility of different elements of course provision; " the extent to which trainees' expectations and preconceptions about ITT vary according to the training route they are following and other variables such as gender, age and previous career histories; " trainees' accounts of their early experiences of ITT, including their early experiences of mentoring and support, and their perceptions of the relationship between different elements of their training (including those based in schools and, where appropriate, higher education institutions); and " possible relationships between trainees' early experiences of ITT and: (a) their preconceptions and expectations; and (b) their previous career histories.