Research into teacher effectiveness has traditionally attempted to uncover generic characteristics of effective teachers. However, recently the realisation that teacher effectiveness may be differentiated across different domains has gained recognition. In this article, we propose that researchers and policy-makers develop more differentiated models of teacher effectiveness. An overview of research is given that looks at whether there is evidence for differentiated effectiveness in four areas: different subject and curriculum areas, pupil background and ability, pupils' personal characteristics, and different teacher roles.