Self-injurious behaviors in correctional facilities have been reported as a significant threat to inmates, staff, and institutional operations. This study is the first national survey to inquire about self-injurious behavior in incarcerated prison populations. Surveys were mailed to mental health professionals working in State facilities that provided mental health services and housed 100 plus inmates. Data were received from 230 respondents representing 473 prison facilities. The average prevalence of inmate self-injury was 2.4 percent, and it was 0.7 percent for serious self-injury. Cutting was reported as the most frequent act of self-injury, with considerable concern for the importation of self-injury tools reported. Treatment responses were typically therapeutic or punitive, with a significant portion of facilities employing suicide protocols to address self-injurious behaviors. Results from negative binomial regressions suggest institutional characteristics associated with the prevalence of inmate self-injury include female-only institutions, specialized maximum-security units, and elevated staffing ratios. Figure, tables, notes, and references (Published Abstract)