Introduction: Using clinical registries to collect and monitor individual, case-level, and population health-relevant variables has been found to be effective at improving outcomes in adult populations. However, due to multiple barriers unique to pediatric care, there are limited available registries for youth and limited studies investigating their effectiveness for pediatric populations. This paper describes a process to develop clinical BH registries to address the BH needs of youth. Method: The registry development process employed a community-hospital-accountable care organization (ACO) stakeholder partnership as part of a population health initiative within the ACO to develop a pediatric focused clinical BH registry. The development process used the exploration, preparation, implementation, sustainment (EPIS) strategy within the implementation science framework. Results: The developed registry collects clinical, operational, and population health relevant variables that are important to guiding the development and sustainment of the initiatives outcomes. Stakeholders have determined the registry to be feasible and to meet the needs of the initiative. Discussion: We created a pediatric clinical BH registry that is sensitive to the unique needs of youth across a broad range of common BH needs. While it is not without limitations, this paper serves as an example of a generalizable process to create functional registries for youth. Limitations and future directions are discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).