Undergraduate students routinely rated science-related courses such as biopsychology as intimidating and very difficult. Identification of factors that may contribute to success in these types of courses is important in order to help increase performance and interest in these topics. To examine what variables are related to performance, we studied undergraduate students enrolled in biopsychology courses. We found grade point average and students' attitudes about science are the best predictors of performance. Level of perceived preparedness, science efficacy, test anxiety, and previous exposure to the course material were also associated. Contrary to previous data, we did not find a significant relationship between gender and race. It appears that to assist students in biopsychology, we need to focus on preparing them better for the course and stimulating a more positive attitude toward the material. (Contains 3 tables.)