Family strengthening is proactively providing strengths-based, supportive services to a whole family unit to promote child well-being and prevent family separation, whether the child is living in their original family, an alternative family placement (e.g., foster or kinship care), or has reunified with family after being previously separated. This chapter provides ways of conceptualizing and categorizing family-strengthening services—primary, secondary, or tertiary prevention—and examples of services in each category that have been used to prevent family separation in various contexts. The chapter reviews the empirical evidence on family-strengthening interventions, highlighting promising findings related to family well-being while noting significant gaps in rigorous evidence, particularly in low- and middle-income countries and in demonstrating direct effects on family separation. Finally, we discuss implications for policy and practice, emphasizing the need for workforce development and financing to scale effective family-strengthening services within government systems.