This study examined reunification outcomes among Mexican immigrant families involved in the child welfare system, and compared characteristics of Mexican-origin and non-immigrant children involved in the child welfare system. An exploratory retrospective longitudinal design using administrative data from two counties in Northern California was utilized. The quantitative sample (N = 2152) included children entering the foster care system for 8 or more days between January 1, 2001 and December 31, 2007 in the two participating counties. Child welfare administrative data (CWS/CMS) were merged with eligibility data (CalWIN) in order to obtain parent and child place of birth and citizenship status. Quantitative measures drawn from the merged CWS/CMS and CalWIN dataset included the following: demographic characteristics, immigrant characteristics, case characteristics and reunification outcomes. Results indicated that a significantly higher proportion of Mexican immigrant families (70.7%) were reunified than non-immigrant families (43.1%). Significant correlates of reunification among Mexican immigrant families included the following: mothers with authorized citizenship status (vs. unauthorized citizenship status), mothers whose primary language was Spanish (vs. English), and children with two or fewer placements (vs. three or more placements). Differences between Mexican-origin and non-immigrant children were that Mexican-origin children were older on average than non-immigrant children, and they were more likely to experience physical abuse, sexual abuse or emotional abuse; they were also more likely to be placed in foster care or a group home (vs. relative care). Implications for social work practice and policy are discussed.