Stem cell pools are dynamic and capable of reacting to insults like injury and starvation. Recent work has highlighted the key role of dedifferentiation as a conserved mechanism for replenishing stem cell pools after their loss, thereby maintaining tissue homeostasis. The testis of the fruit fly Drosophila melanogaster offers a simple but powerful system to study dedifferentiation, the process by which differentiating spermatogonia can revert their fate to become fully functional germline stem cells (GSCs). Dedifferentiated GSCs show interesting characteristics, such as being more proliferative than their wild-type sibling GSCs. To facilitate the study of the cellular and molecular mechanisms underlying the process of germline dedifferentiation in the Drosophila testis, here we describe techniques for inducing high rates of dedifferentiation and for unambiguously labeling dedifferentiated GSCs.