This study investigated the psychometric properties of self-regulating capacity in vocabulary learning scale (Tseng, Dornyei, & Schmitt, 2006) in the Iranian EFL context. For this purpose, a sample of 1167 high school students completed the Persian SRCvoc in the main phase. The internal consistency reliability of the scale was examined using Cronbach’s alpha. It showed acceptable reliability in both piloting and main phases. The results of exploratory factor analysis (EFA) showed that the SRCvoc is composed of three factors. However, confirmatory factor analysis (CFA) on the three-factor model of the SRCvoc and Tseng et al.’s (2006) five-factor model of the SRCvoc with item-level indicators showed that both models did not fit the data. The findings of this study imply that the item-parcels in Tseng et al. (2006) may have masked the nature of the factor structure of the self-regulating capacity in vocabulary learning scale. It should therefore be re-theorized.