IntroductionThis chapter explores (i) how different types of research are fundamental in informing programme content (research in teacher education) and (ii) how teacher education research is also useful in influencing programme design and structure (research on teacher education) (Cochran-Smith and Demers, 2008). The discussion of research in teacher education will present a rationale for research-rich teacher preparation and development and then review three different types of research: pedagogical content knowledge, professional enquiry, and innovative modes of integrating theory and practice. The analysis of research on teacher education will pay particular attention to the insights gleaned into how teachers learn, and illustrate how this knowledge has informed the content of teacher preparation courses. In addition to exploring the benefits and value of research in and on teacher education, the chapter will examine some of the associated challenges: the tensions between competence based teacher standards and a wider professional understanding, the contested nature of 'valid' educational research, issues related to teacher educators' research capacity, and the difficulties in developing an evidence base in teacher education.The focus of this book is on teacher education across the UK and Ireland. This chapter focuses primarily on the four nations within the UK, although many of the points made have clear relevance to Ireland (and see also Chapter 8 by O'Doherty where the place of research in Irish teacher education is discussed), and indeed internationally. It begins with a brief overview of the policy context for teacher education research in each of the four jurisdictions of the UK. Those issues will then 2 be readdressed in the discussion section with respect to the key points made in the chapter.