This qualitative study examines student learning experiences toward a student-developed case study activity for online discussion guided by a three-tier case method model. Forty-five students were recruited from four online adult education courses. Analysis of students' feedback shows that this activity leads to students' positive learning experiences, including provoking critical thinking towards the discussion topic and providing unique resources for adult educators. The student-developed case study activity also helps establish a supportive peer relationship and engages students through analyzing a variety of student-developed cases, as well as interacting with the instructor and exchanging ideas with peers. This study furthermore indicates the potential usefulness of the proposed model as a guide for case study activities in the field of adult education and beyond.