This paper presents a study of the reasons for failure of final year students on a four-year initial teacher training course. The aims were: to investigate reasons for student-teacher failure on the final teaching practice; to develop a model of teacher development based on shared understandings of the process of learning to teach, between university supervisors, teachers in partnership schools, and student-teachers. There were three strands to the research methodology: 1) Analysis of a sample of observation booklets from all four years of the BEd, including all failing students, and a selection of 'average' and 'outstanding' students; 2) Group interviews with a sample of teachers who have had outstanding or failing students on the final placement in 2000; 3) Group interviews with a sample of full and part time supervisors. Transcripts of interviews and observation booklets were analysed according to categories developed partly from the data themselves, and partly from Turner-Bisset's (2001) model of levels of reflection. The findings from this study have the potential to inform teacher development and initial teacher education in Europe and beyond. Issues of wastage, failure and retention are of considerable importance especially in contexts of teacher shortages.