This study consisted of three main phases including the development of a hypothesised model of language identity in Iran, developing and validating a questionnaire based on this model and finally testing the model based on the questionnaire data. In the first phase of this research, a hypothesised model of language identity in Iran was developed based on the literature and consultations with a panel of experts. After that, a questionnaire was developed and validated to tap the components of the hypothesised model. In order to develop this questionnaire, the researchers went through a number of rigorous steps including content selection, item generation, writing the rating scales and personal information part, expert opinion, item revision, initial piloting, reliability estimation and finally validation. The results of the questionnaire administration indicated that the reliability of the questionnaire estimated through Cronbach's alpha was 0.73 and exploratory factor analysis also identified six factors. As the final phase of this study, structural equation modelling through AMOS 21 was utilised to test the model. The initial results showed a poor fit model; however, the model was trimmed by removing one item from the questionnaire, and final statistical indices indicated that the model was fit.