Research into self-regulating capacity in vocabulary learning is recognized as a significant topic within the second language domain. The self-regulating capacity in vocabulary learning scale (SRCvoc; Tseng et al. 2006) is arguably the most widely used tool for assessing this construct. The common factor model, which is applied through confirmatory factor analysis and exploratory factor analysis, has been the primary methods for validating the SRCvoc. However, previous studies have encountered difficulties in obtaining good model fit and generated results that deviate from supporting the theory. We argue the constructs of the SRCvoc are inherently "composites," rather than "common factors," and should therefore be evaluated using confirmatory composite analysis. In this study, we compared the results of CFA and CCA, highlighting the shortcomings of CFA in supporting the construct validity of composite constructs such as SRCvoc. CFA failed to satisfy the conceptual and empirical perspectives of SRCvoc. In contrast, our data supported the construct validity of SRCvoc solely through CCA. We also evaluated the criterion-related validity of SRCvoc via the composite model and showed that SRCvoc constructs were positively and moderately associated with L2 vocabulary achievement.