Observation is a powerful tool for assessing teachers to ensure teachers' professional growth. Used well, it can provide a clear and accurate picture of teachers and teaching. The aim of this study is to assess the underlying structure and psychometric properties of the Language Teacher's Observation Scale (LTOS) among Iranian EFL teachers. So, a six component model of English teacher observation, encompassing preparing for the lesson, cognitive considerations, metacognitive considerations, social-interaction considerations, classroom management, teacher behavior and personality, and teacher knowledge was developed. Data was obtained from 540 Iranian English teachers. Half the sample was used for exploratory factor analysis, with the holdout sample used for confirmatory factor analysis. EFA was conducted via SPSS and CFA was conducted via Partial least squares (PLS) estimation method.
