Research has found psychological dimensions of religiosity/spirituality (R/S) beneficial against non-suicidal self-injury (NSSI), whereas the effect of R/S social aspects is less studied. Using data from the SAMINOR 2 Questionnaire Survey (2012, n=10,717 ages 18-69; response rate: 27%; non-Sami: 66%; females: 55%), we examined the association of R/S-religious attendance, congregational affiliation, Laestadian family background, religious importance/view of life-with NSSI in the adult Sami and non-Sami population of Arctic Norway. We also applied multivariable-adjusted regression models and mediation analyses to explore how religious participation transmits its effect on NSSI through violence exposure and symptoms of anxiety and depression.Across ethnicities, 3.3 percent (n=355) reported lifetime NSSI-ranging from 1.2 percent among Laestadians to 7.7 percent in unaffiliated. Regular religious attendance had a significant negative total effect on NSSI (OR=0.59), seemingly transmitting 95 percent of the effect via fewer anxiety and depression symptoms-probably related to religious social support.