This review describes developments in epilepsy research during the last 3 to 4 decades that focused on the dentate gyrus (DG) and its role in temporal lobe epilepsy (TLE). The emphasis is on basic research in laboratory animals and is chronological, starting with hypotheses that attracted a lot of attention in the 1980s. Then experiments are described that addressed the questions, as well as new methods that often made the experiments possible. In addition, where new questions arose and the implications for clinical epilepsy are discussed.