Primary care providers were surveyed to determine how prepared they feel to address nonsuicidal self-injury (NSSI) among adolescents, their interest in training on NSSI, and factors associated with routinely asking about NSSI when providing health supervision. Participants included family medicine physicians (n = 260), pediatricians (n = 127), family nurse practitioners (n = 96), and pediatric nurse practitioners (n = 54). Almost 50% felt unprepared to address NSSI, and over 70% wanted training in this area. Overall, relative to other areas of mental health care, clinicians felt least prepared to address and wanted more training on NSSI. Just 27% reported they routinely inquired about NSSI during health supervision. Factors associated with routinely asking about NSSI were identifying as female (OR = 2.37; 95% CI = 1.25–4.49), feeling better prepared to address NSSI (OR = 1.51; 95% CI = 1.04–2.20), and more frequently using a psychosocial interview to identify adolescents in distress (OR = 1.23; 95% CI = 1.02–1.48). Teaching clinicians to assess NSSI within a psychosocial interview may increase screening for and identification of the behavior among adolescents in primary care.