Background: Many mental health professionals (MHPs) encounter youth at risk for suicide but lack knowledge and confidence to assist these individuals. Unfortunately, training for MHPs on suicide risk assessment and management is often not adequately accessible. Aims: The aim of this study was to evaluate whether MHPs' knowledge, attitudes, perceived social norms, and perceived behavioral control in working with at-risk suicidal youth improve following an online training (QPRT: Question, Persuade, Refer, Treat). Method: QPRT was provided to 225 MHPs from three large urban areas in the United States. Suicide prevention literacy, attitudes, perceived social norms, and perceived behavioral control in assessing and managing suicide risk were assessed before and after training. Data were also collected on training engagement and completion. Results: Suicide prevention literacy in most competency domains and perceived behavioral control increased significantly after participation in QPRT. Suicide prevention attitudes and some knowledge domains did not significantly improve. MHPs reported high satisfaction with the training. Conclusion: The current study provides initial support for offering MHPs online suicide risk assessment and management training. Online training programs may be an engaging and feasible means for providing advanced suicide prevention skills to MHPs who may have numerous barriers to accessing face-to-face training.