Background: Young people who have psychiatric problems are more likely than their peers to endure difficulties during their sexual and gender identity development.Aim: This study aims to examine the communication between mental health care providers and their patients about the topics of relations, sexuality and gender identity, including a description of professionals' attitudes toward these topics and the factors that contribute to and inhibit communication. Methods: Study participants (n = 242, response rate = 31%) were a representative sample of a large multicenter cohort of 768 mental health care professionals (eg, medical doctors, psychiatrists, psychologists, group counselors, parent counselors) of 7 institutions and 5 solo practices in the Netherlands, who completed a survey on communication about sexuality and gender identity with their young patients (age 12−21 years). Outcomes: Sexuality and gender identity are infrequently discussed by mental health care providers with their young patients or their patients' parents.Results: Of the study sample, 99.5 % valued sexuality as an important topic to discuss with their patients. However, only 17.1% of the professionals reported that they discussed sexuality-related issues with the majority (>75%) of their patients (adolescents: 19.9%, parents: 14.4%) Additionally, only 2.3 % of the participants discussed gender nonconformity regularly with patients. Information about sexual side effects of prescribed medication was infrequently (20.3%) provided: antidepressants (40.0%), antipsychotics (34.0%), benzodiazepines (5.1%) and stimulants (2.4%). The most frequently cited reasons for not discussing these topics were a lack of awareness, own feelings of discomfort, and the patients' supposed feelings of shame. There was no gender differences observed. Clinical implications: Recommendations for professionals include to be aware of these topics, initiating ageappropriate conversation and use inclusive language. Strengths and limitations: The present study included a diverse and representative group of mental health care professionals. Frequency of sexual communication was based on self-report, which brings a risk of bias. Conclusion: Despite a recognized need to engage in age-appropriate communication about sexuality and gender identity in youth mental health care, mental health providers seem to remain hesitant to discuss such topics. Bungener SL,