Active-learning strategies are increasingly being integrated into college-level science courses to make material more accessible to all students and to improve learning outcomes. One active-learning pedagogy, case-based learning (CBL), was developed as a way to both enhance engagement in the material and to accommodate diverse learning styles. Yet, adoption of CBL approaches in undergraduate biology courses has been piecemeal, in part because of the perceived investment of time required. Furthermore, few CBL lesson plans have been developed specifically for upper-division laboratory courses. Here, we describe four cases that we developed and implemented for a senior cell and molecular biology laboratory course at San Francisco State University, a minority-serving institution. To evaluate the effectiveness of these modules, we used both written and verbal assessments to gauge learning outcomes and attitudinal responses of students over two semesters. Students responded positively to the new approach and seemed to meet the learning goals for the course. Most said they would take a course using CBL again. These case modules are readily adaptable to a variety of classroom settings. (Contains 3 tables and 4 figures.)