This paper is based upon a unique mixed methods 4-year research project which focused upon the variations in teachers' work, lives, and effectiveness of 300 elementary and secondary school teachers in a range of 100 schools across seven regions of England. Its findings challenge linear conceptions of teacher development and expertise and provide new understandings of the effects of personal, school and broader policy contexts upon professional life phase trajectories and teachers' emotional identities. It finds connections between these and teachers' commitment, resilience, and effectiveness. This paper discusses these in relation to the school standards and teacher retention agendas.