Background: Technology is increasingly being used in youth mental healthcare to support service delivery and improve health outcomes. The current study trialed a new electronic psychosocial application (myAssessment) that aims to provide a holistic assessment of relevant risk and protective factors in youth mental healthcare. The study aimed to determine whether myAssessment was acceptable to all users, and whether it affected: reporting of certain behaviors and ratings of self-disclosure; youth ratings of control, fears of judgmental reactions or time-efficiency; clinician ratings of time-efficiency or their ability to formulate a treatment plan; and the therapeutic alliance. Method: The application was tested at a youth mental health service using a quasi-experimental two phase Treatment-as-Usual/Intervention design. Three hundred thirty nine youth and 13 clinicians participated across both phases. Reporting of behaviors, self-disclosure, youth control, judgmental reactions, time efficiency, ability to formulate treatment plans, and the therapeutic alliance were compared between groups. Results: myAssessment was found to be widely accepted by both young people and clinicians. Use of myAssessment resulted in reporting of behaviors that were 2.78 through 10.38 times higher for a variety of substances (use of tobacco, alcohol, cannabis, sedatives, hallucinogens, and opioids), in identifying non-heterosexual sexual orientation, having had sex, an STI check, sex without a condom, having felt pressured to have sex in the past, having self-harmed, and in having put themselves in an unsafe situation. Participants who used the application also reported being less likely to lie on past experiences of being bullied, substance use, and self-harm. Use of the application resulted in improved youth ratings of time efficiency in session. The application was found to have no impact on youth control, judgmental reactions, formulation of treatment plans, or the therapeutic alliance. Conclusions: Electronic psychosocial assessments can increase rates of self-disclosure and, therefore, provide an earlier and more comprehensive picture of young people’s risks without negatively impacting the therapeutic alliance. Additionally, this type of technology has been shown to be widely accepted by both young people and clinicians and can improve youth beliefs that there is enough time in session to speak about what is most important to them. [ABSTRACT FROM AUTHOR]