Background and purpose: Access to evidence-based mental health care for children is an international priority. However, there are significant challenges to advancing this public health priority in an efficient and equitable manner. The purpose of this international colloquium was to convene a multidisciplinary group of health researchers to build an agenda for addressing disparities in mental health care access and treatment for children and families through collaboration among scholars from the United States and Europe engaged in innovative implementation science and mental health services research. Key highlights: Guided by the Exploration, Preparation, Implementation, and Sustainment (EPIS) Framework, presentations related to inner, outer, and bridging context factors that impact the accessibility and quality of mental health evidence-based practices (EBPs) for children and families. Three common topics emerged from the presentations and discussions from colloquium participants, which included: 1) the impact of inner and outer context factors that limit accessibility to EBPs across countries, 2) strategies to adapt EBPs to improve their fit in different settings, 3) the potential for implementation science to address emerging clinical and public health concerns. Implications: The common topics discussed underscored that disparities in access to evidence-based mental health care are prevalent across countries. Opportunities for crosscountry and cross-discipline learnings and collaborations can help drive solutions to address these inequities, which relate to the availability of a trained and culturally appropriate workforce, insurance reimbursement policies, and designing interventions and implementation strategies to support sustained use of evidence-based practices.