Using Ireland as an example, this paper explores the rationale behind various selection criteria currently used to select suitable candidates for initial teacher education courses. It investigates and discusses patterns of association between second-level student teachers' background characteristics on entry to their teacher education programme Professional Diploma in Education (PDE) and their achievement in terms of their final academic and teaching practice grades. It draws on a longitudinal analysis of application and examination data collected from eight student teacher cohorts (2000-2007, N = 1,023) who completed their second-level initial teacher education at one Irish university. Special attention will be paid to the predictive value of entrants' prior academic performance and teaching experience for their success in the academic as well as practical components of their teacher education course. The quality rationale behind academic selection criteria is contested on the basis of findings from this study. The positive impact of prior teaching experience on teaching practice performance and the differences in achievement observed between students from different academic fields are discussed.