Partnerships between public schools and mental health agencies are essential to the delivery of school-based mental health services, especially for underresourced and minoritized youth and families who face barriers to mental health care in the community. Yet little is known about the barriers and facilitators of partnerships or how they have changed pre– and post–COVID-19 school closures. This study identifies target areas to strengthen school-mental health partnerships to improve access to and delivery of school-based mental health services during increased youth mental health need and rapid transformation of mental health services in California.