Schommer Epistemological Questionnaire (SEQ) has been widely used in varying purposes providing significant input to the growing body of epistemological research. However, there is no consensus regarding its factor structure. Since researchers in teacher education still use the said instrument, the study aimed to investigate both the dimensionality and predictive validity of SEQ. Data came from 229 pre-service teachers of a public university in Cagayan Valley Region, Northern Philippines. The dimensionality of SEQ was analyzed using Confirmatory Factor Analysis (CFA), and its predictive validity was examined through Structural Equation Modeling (SEM). CFA results showed a one-dimensional structure, which contends the multidimensionality of epistemological beliefs as initially theorized by Schommer. Moreover, SEM analysis provides evidence that the one-dimensional epistemological beliefs extracted in the study possess predictive validity as the theoretical model successfully accounts for the observed relationship between epistemological beliefs and professional education grade. Hence, SEQ may still be used as a valid measure in the context of the study only if treated as a one-dimensional scale.