This paper investigated the quantitative phase of an exploratory sequential mixed methods research. The main purpose of this study was to develop and validate a Teachers‟ Assessment Identity (TAI) question- naire based on the dimensions and factors found in the first part of the study. The extracted factors from interviews along with the theoretical framework formed the basis for the generation of the pool of items, which later reduced to 46 items for eventual inclusion in TAI questionnaire. This initial draft of the scale was revised and re-worded based on the comments offered by assessment experts and teachers. The de- signed questionnaire was then distributed to 384 EFL teachers. Normality and reliability of data were measured using SPSS. Construct validity of the designed scale was assessed through CFA with AMOS 24. The results derived from the statistical analysis indicated that TAI questionnaire had a good model- data fit, and the factor loadings and reliability values were at a satisfactory level. The findings showed that the Teachers‟ Assessment Identity (TAI) questionnaire contained three dimensions i.e. assessing as- sessment literacy, dispositions, and contextual factors. This questionnaire could be used as a valid and reliable scale for teachers as assessors. Manuscript profile