The present study examined the relationship between sexual behaviors and mental disorders and suicidality in the National Comorbidity Survey Replication, a representative sample of adults ages 18 years and older (N = 5,692). The World Health Organization Composite International Diagnostic Interview was used to make DSM-IV based disorder diagnoses. Participants were also asked about suicidality and sexual behaviors. Multiple logistic regression analyses adjusted for sociodemographic variables were used to examine the relationships of three sexual behaviors (age of first intercourse, number of past year partners, and past year condom use) with 15 mental disorders (clustered into any mood, anxiety, substance use, and disruptive behavior groups) and suicidality (ideation and attempts). Compared to ages 15-17, those with age of first intercourse between 12 and 14 had increased rates of lifetime disruptive behavior, substance use, and any mental disorder, and suicidal ideation and attempts (adjusted odds ratio (AOR) range, 1.46-2.01). Those with age of first intercourse between ages 18-25 and 26-35 were at decreased likelihood of several lifetime disorder groups (AOR range, 0.19-0.81). Individuals who had two or more sexual partners in the past year had increased rates of all past year disorder groups examined (AOR range, 1.44-5.01). Never married participants who rarely/never used condoms were more likely than those who always used condoms to experience any mood, substance use, and any mental disorder, and suicide attempts (AOR range, 1.77-8.13). Future research should longitudinally examine these associations and account better for possible familial and personality confounders.