In numerous organs, tissue injury is repaired through compensatory proliferation, a regenerative injury response which leads to restoration of tissue morphology and mass. However, numerous tissues have been shown to respond to tissue injury by a distinctly different, non-proliferative process known as hypertrophy. Following injury, hypertrophic tissues increase the size and DNA copy number (ploidy) of remaining cells to restore lost organ mass. While hypertrophy is clearly important to repairing numerous injured organs such as the mammalian liver, this repair process does not always restore tissue morphology and function. Thus, understanding molecular differences between hypertrophy and the more regenerative compensatory proliferation process could improve efforts to regenerate organs. To approach this question, we established that the Drosophila pylorus undergoes compensatory proliferation when injured during juvenile (larval) stages, and then switches to a hypertrophic repair program when injury occurs during adulthood. Studying this process, we can now molecularly interrogate the regulation underlying the decision to undergo hypertrophic or proliferative injury responses. We will discuss recent work identifying the time frame in which the switch between proliferation and hypertrophy occurs. This study provides valuable new insights into conserved mechanisms of organ injury repair using a novel model system.