Teacher identity has recently been under extensive investigations to understand its impacts on and relationships with classroom variables. Considering the effect identity has on individuals, an immediate relationship is that between teacher identity and an index of an effective teaching, i.e. teacher efficacy. The present study tries to understand the possibility of a direct relationship between the two concepts. 37 English teachers were given an efficacy scale to gauge and rank their efficacy indices. The top 5 participants in teacher efficacy list were then regularly observed during an academic semester and interviewed to study their institutional identity. Meanwhile, similar procedure was conducted for 5 teachers with the least teacher efficacy scores, too. Detailed qualitative analysis of interview transcriptions and observation notes revealed the two groups were distinct regarding their institutional identity. In other words, it was shown that institutional identity and teacher efficacy were positively associated with each other.