In an effort to test the effectiveness of teaching and learning strategies that may increase biological literacy for nonbiology majors, an NSF-funded research project called "The Slice of Life," was conducted from 1994 to 1998. In the present study, a selfefficacy instrument was constructed and designed specifically for the project to determine students' self-reported confidence in understanding and using biology in their lives. Based on social cognitive theory, the premise for developing such an instrument was that a specific measure of biological self-efficacy was deemed to be an important predictor of the change processes necessary to improve students' biological understanding. Results of this study indicate that the Biology Self-Efficacy Scale was a valid and reliable tool for studying nonbiology majors' confidence in mastering biological literacy. Factor analysis supported the contention that the Biology Self-Efficacy Scale was a multidimensional construct consisting of at least three dimensions: methods of biology; generalization to other biology/science courses and analyzing data; and application of biological concepts and skills. These dimensions represent three components of biological literacy that have been commonly described in the literature. The instrument may lead to further understanding of student behavior, which in turn can facilitate the development of strategies that may increase students' desire to understand and study biology. More specifically, by using the self-efficacy tool as a pre-and posttest indicator, instructors can gain insight into whether students' confidence levels increase as they engage in more complex tasks during the course, and, in addition, what type of teaching strategies are most effective in building