We review empirical studies on kinship foster care in the United States. We conceptualize kinship foster care within the context of Urie Bronfenbrenner's (1994) most recent ecological systems theory. Because there are multiple levels of influences on the developmental outcomes of children placed in kinship foster home, understanding the interrelations between the individual (child) and his or her surrounding environments (e.g., biological families, social-support network) is important. We argue that Bronfenbrenner's most recent ecological systems theory is an appropriate theoretical framework for policy and practice implications in addressing complex issues surrounding kinship foster care system in the United States. This review integrates the empirical findings collectively on the factors associated with kinship foster care within and between five systems levels of the ecological systems theory: "micro-" (caregiver-child relationship, attachment, and kinship family environment), "meso-" (biological families), "exo-" (social-support network outside the family), "macro-" (race/ethnicity and policies), and "chrono-" (welfare reform) systems levels. Theories that are relevant to the ecological factors (e.g., attachment theory) are also discussed. Finally, we draw policy and practice implications from the ecological systems analysis.