The purpose of this study was to determine the predictors of student grades in introductory physics courses utilizing problem-based learning (PBL) approach and traditional lecturing. The study employed correlational/predictive methods to investigate and describe/explain relationships of students' physics grades with their expectations, attitudes, epistemological beliefs about physics and physics learning, and demographic variables. The subjects involved in this study were 264 freshmen engineering students (PBL, n = 100; traditional, n = 164) at Dokuz Eylul University (DEU) in Izmir, Turkey. All students were surveyed at the beginning and at the end of the spring 2007 semester using the Maryland Physics Expectations Survey (MPEX) to determine their expectations, attitudes, and epistemological beliefs about physics and physics learning. Students' physics learning was measured via their end of semester physics grades. Correlational analyses indicated significant relationships between variables of the study. Forward stepwise linear regression analyses revealed the effort cluster and selected background variables (e.g., gender) as significant predictors of physics grades. Results suggest that further study is needed to investigate predictors and correlates of students' physics learning using qualitative measures to support and more clearly interpret the numerical findings. (Contains 5 tables.)