All species in a community interact, and understanding the ecological interactions between the target species and members of the receiver community is thought to be important for successful translocation. It’s increasingly common for practitioners to consider how the target species will interact with predators that are present at the receiver site and to mitigate depredation through predator removal or to incorporate predator training into pre-release preparation procedures. But, to our knowledge, no study has evaluated the efficacy of heterospecific competitor experience. The Pacific pocket mouse (Perognathus longimembris pacificus) is one of the most critically endangered mammals in southern California, USA with just three small, isolated populations known to remain extant. P. l. pacificus lives in a community where multiple species of native rodents have overlapping diets. It is the smallest species in the guild and is behaviorally subordinate to the larger species present at receiver sites. Repeated aggressive interactions from resident heterospecific competitors could prevent translocated pocket mice from establishing burrows during the critical settlement period and reduce fitness. Direct removal of competitors is conducted to allow the species to become established, but is not a viable strategy to facilitate community integration and long-term persistence. We tested whether giving captive-born mice pre-release experience with a heterospecific competitor would modify their behavior and improve translocation outcomes. Our results indicate that mice trained with a heterospecific competitor are more likely to survive than those that did not receive training. These results highlight the important of considering interspecific interactions during translocation.