The interpersonal psychological theory of suicide (IPTS) was used to examine suicidal thoughts and behaviors among 129 transgender and gender nonconforming (TGNC) youth. Youth were categorized according to their gender identities: female-to-male (FTM), male-to-female (MTF), female-to-different-gender (FTDG), and male-to-different gender (MTDG). Higher percentages of suicidal ideation were reported by FTDG and FTM youth; and higher percentages of suicide attempts by FTDG and MTDG youth. Perceived burdensomeness and thwarted belongingness were significantly related to suicidal ideation and/or suicide attempts. Experiences of painful, provocative and harmful events and acquired capability significantly predicted suicide attempts. The findings support IPTS in explaining suicidal behaviors among TGNC youth. Implications for prevention and intervention efforts are discussed.