This field guide is a first step by a collaborative of California child-serving education, health, and social service experts and leaders to further California's current efforts toward one effective, integrated, comprehensive, school-based child-serving system. The guide includes guidance for both local education agencies (LEAs) and state leaders, with details and implementation guidance on a wide variety of cross-sector initiatives to support the whole child. Using a whole-child approach, this guide outlines resources and strategies for LEAs and state leaders to use to support the implementation of funding that centers children and families. The guide includes six major initiatives that can serve as part of an integrated, school-based system of care: Adverse Childhood Experiences (ACES) Aware Initiative, Children and Youth Behavioral Health Initiative (CYBHI), Children and Youth System of Care, community schools initiatives, early childhood initiatives, and expanded learning. The guide also focuses specifically on how to fund various components of an integrated, school-based system of care, providing strategies for funding sustainability and further details about funding sources for comprehensive services. The guide concludes with a discussion of how state leaders facilitate the ability of LEAs to establish integrated, school-based systems of care by modeling cross-sector collaboration at the state level to reduce the current barriers that LEAs face. [This guide was produced with Breaking Barriers, California Alliance of Child and Family Services, and the Santa Clara County Office of Education.]