ABSTRACT: Importance:Gender identity conversion efforts (GICE) have been widely debated as potentially damaging treatment approaches for transgender persons. The association of GICE with mental health outcomes, however, remains largely unknown. Objective:To evaluate associations between recalled exposure to GICE (by a secular or religious professional) and adult mental health outcomes. Design, Setting, and Participants:In this cross-sectional study, a survey was distributed through community-based outreach to transgender adults residing in the United States, with representation from all 50 states, the District of Columbia, American Samoa, Guam, Puerto Rico, and US military bases overseas. Data collection occurred during 34 days between August 19 and September 21, 2015. Data analysis was performed from June 8, 2018, to January 2, 2019. Exposure:Recalled exposure to GICE. Main Outcomes and Measures:Severe psychological distress during the previous month, measured by the Kessler Psychological Distress Scale (defined as a score ?13). Measures of suicidality during the previous year and lifetime, including ideation, attempts, and attempts requiring inpatient hospitalization. Results:Of 27?715 transgender survey respondents (mean [SD] age, 31.2 [13.5] years), 11?857 (42.8%) were assigned male sex at birth. Among the 19?741 (71.3%) who had ever spoken to a professional about their gender identity, 3869 (19.6%; 95% CI, 18.7%-20.5%) reported exposure to GICE in their lifetime. Recalled lifetime exposure was associated with severe psychological distress during the previous month (adjusted odds ratio [aOR], 1.56; 95% CI, 1.09-2.24; P?