We examined the incidence, characteristics, and predictors of separations of children from mothers in 543 poor families receiving public assistance, 251 of whom had experienced homelessness during the previous 5 years. Forty-four percent of the homeless mothers and 8% of housed mothers were separated from one or more children. A total of 249 children were separated from 110 homeless families and 34 children from 23 housed families. Children were placed with relatives and in foster care but were rarely returned to their mothers. Maternal drug dependence, domestic violence, and institutionalization predicted separations, but homelessness was the most important predictor, equivalent in size to 1.9 other risk factors. We infer that policies regarding child welfare and substance abuse treatment should be changed to reduce unnecessary placements. Studies of homeless children who remain with families may be biased if separated children are excluded.