This study examined whether children who become homeless differ from other low-income children in their mental health service use before and after their first homeless episode, and to what extent homelessness is associated with an increased likelihood of mental health service use. Differences between children with and without new onset of sheltered homelessness in the use of mental health services emerged following homelessness and widened over time. Sheltered homelessness and foster care placement history were associated with increased odds of receiving inpatient and ambulatory mental health services. Findings underscore the importance of collaborations between homeless assistance, foster care, and mental healthcare in efforts to mitigate family homelessness and collateral needs among homeless children.