This paper reports on a qualitative multiple case study that examined the implementation of innovations in English language education by three teachers in Hong Kong. Grounded in an analytical framework of teacher identity, in-depth interviews over an entire year provide a longitudinal understanding of the participants' experiences of simultaneously negotiating identity and implementing innovation in language teaching and learning within different schools in Hong Kong. Results point to a mutually constitutive relationship between identity and the implementation of these innovations. It is argued that the implementation of innovation underpinned the capacity of participants to both position themselves, as well as to be positioned by others, as particular types of teachers. The results also suggest that being afforded scope to explore their preferred professional identities, both discursively and experientially, is essential to the implementation of innovation. The analysis highlights that the implementation of innovation can be blocked or restricted if scope for the exploration of particular identities is denied to teachers, and that this may result in the marginalization of the identities teachers are seeking to construct. Implications for schools wishing to foster the implementation of innovation in language teaching and learning are discussed and suggestions for future research considered.