This article gives just a taster of a large-scale in-depth longitudinal research project, "Variations in Teachers' Work, Lives and Effectiveness", funded by the Department for Education and Skills (DfES) and conducted by a joint team from the University of Nottingham and the Institute of Education, London. The authors outline the approach which the research adopted, highlight the key findings and discuss some of the implications of this ground-breaking study, which established the dynamic, emotional nature of the professional life phases and identities of teachers. They suggest that what it really means to be a teacher is not only more complex than some current wisdom suggests, but that schools need to devote far more attention to their policies and strategies for making the best of their precious human resource.