With the emerging trend of researching teacher identity from using qualitative approach to adopting quantitative or mixed-methods approach, it is essential and significant to develop instruments for measuring this construct. This paper reports on the development and validation of a measurement tool, the English Teacher Identity Measure (ETIM). ETIM is designed to measure in-service English teachers' identity levels. In accordance with DeVellis (2017) scale development guidelines, ETIM was developed following the procedure: (a) defining the construct and identifying indicators; (b) creating item pool; (c) seeking expert advice and validating the translation. The psychometric properties of the ETIM were explored on two separate participant groups. First, the initial 24-item ETIM was piloted online with 103 Chinese university EFL teachers for factor structure. The exploratory factor analysis (EFA) resulted in a 19-item scale with four factors: (a) future perspective, (b) career perception, (c) teacher belief, and (d) self-efficacy. Secondly, the 19-item ETIM was used to collect data from 331 university EFL teachers in a provincial capital city. The confirmatory composite analysis (CCA) using Smart PLS3.3.9 software confirmed the 19-item ETIM. The applications of the ETIM are discussed, and recommendations for future research are made in this paper.