Using an action research model, biology faculty examined, implemented, and evaluated learner-centered instructional strategies to reach the goal of increasing the level of student achievement in the introductory biology course BIO 181: Unity of Life I, which was characterized by both high enrollments and a high DFW rate. Outcomes included the creation and implementation of an assessment tool for biology content knowledge and attitudes, development and implementation of a common syllabus, modification of the course to include learner-centered instructional strategies, and the collection and analysis of data to evaluate the success of the modifications. The redesigned course resulted in greater student success, as measured by grades (reduced %DFW and increased %AB) as well as by achievement in the course assessment tool. In addition, the redesigned course led to increased student satisfaction and greater consistency among different sections. These findings have important implications for both students and institutions, as the significantly lower DFW rate means that fewer students have to retake the course. (Contains 8 figures and 3 tables.)