This study investigated factors influencing Force and Motion Conceptual Evaluation (FMCE) pretest and post-test scores for a sample (N = 1116 students) collected in the introductory calculus-based mechanics class at a large eastern land-grant university. Several academic and noncognitive factors were examined using correlation analysis and linear regression analysis to understand their relation to students' physics conceptual understanding. High school physics preparation was the most important factor in predicting FMCE pretest score. The kind of high school physics class (normal or Advanced Placement) and the student's academic performance in that class also greatly affected pretest scores. The optimal linear regression model explained 28% of the variance of pretest scores. Controlling for pretest score, ACT or SAT verbal and mathematics scores, students' grade expectation, and self-efficacy significantly predicted post-test score. The optimal linear regression model explained 54% of the variance of post-test scores. Pretest scores completely captured the effect of high school preparation on post-test scores; if pretest scores were included in a model predicting post-test scores, then high school physics preparation variables were not significant. Gender differences were observed on both the pretest and the post-test. These differences were not substantially mediated by either academic or noncognitive factors.