Suicide prevention remains a challenge across communities in North America and abroad. We examine a suicide prevention effort that is widely used, termed gatekeeper training. There are 2 aims: review the state of the evidence on gatekeeper training for suicide prevention, and propose directions for further research. Method: Studies were identified by searching MEDLINE (PubMed) and PsycINFO from inception to the present for the key words suicide, suicide prevention, and gatekeeper. In addition, a manual scan of relevant articles' bibliographies was undertaken. Results: Gatekeeper training has been implemented and studied in many populations, including military personnel, public school staff, peer helpers, clinicians, and Aboriginal people. This type of training has been shown to positively affect the knowledge, skills, and attitudes of trainees regarding suicide prevention. Large-scale cohort studies in military personnel and physicians have reported promising results with a significant reduction in suicidal ideation, suicide attempts, and deaths by suicide. Conclusions: Gatekeeper training is successful at imparting knowledge, building skills, and molding the attitudes of trainees; however, more work needs to be done on longevity of these traits and referral patterns of gatekeepers. There is a need for randomized controlled trials. In addition, the unique effect of gatekeeper training on suicide rates needs to be fully elucidated.