This paper investigates the five-year prevalence of child welfare services involvement and foster care placement among a population-based cohort of births in a large US city, by housing status of the mothers (mothers who have been homeless at least once, other low-income neighborhood residents, and all others), and by number of children. Children of mothers with at least one homeless episode have the greatest rate of involvement with child welfare services (37%), followed by other low-income residents (9.2%), and all others (4.0%). Involvement rates increase with number of children for all housing categories, with rates highest among women with four or more births (33%), particularly for those mothers who have been homeless at least once (54%). Among families involved with child welfare services, the rate of placement in foster care is highest for the index children of women with at least one episode of homelessness (62%), followed by other low-income mothers (39%) and all others (39%). Half of the birth cohort eventually involved with child welfare services was among the group of women who have ever used the shelter system, as were 60% of the cohort placed in foster care. Multivariate logistic regression analyses reveal that mothers with one or more homeless episodes and mothers living in low-income neighborhoods have significantly greater risk of child welfare service involvement (OR = 5.67 and OR = 1.51, respectively) and foster care placement (OR = 8.82 andOR= 1.59 , respectively). The implications for further research, and for child welfare risk assessment and prevention are discussed. Specifically, the salience of housing instability/homelessness to risk of child welfare service involvement is highlighted.