This research brief draws on the Family Options Study--a U.S. Department of Housing and Urban Development-sponsored study conducted to determine whether the offer of a particular type of housing program helps a homeless family achieve housing stability and other positive outcomes for family well-being--to inform the Department of Health and Human Services (HHS) and HHS grantees in their efforts to prevent and end homelessness of families, children, and youth. It describes the experiences of the studys 1,857 adult heads of households, 677 other adults identified as spouses or partners, and the 4,341 children who were part of the families at shelter entry. Results suggest that housing and family instability are related, and families who stay in emergency shelters have dynamic family structures. About 30 percent of sheltered homeless families reported separation from at least one family member. Family transitions continued in the 20 months after being in an emergency shelter. For example, 10 percent of families experienced new child separations, while 8 percent reported reunification with children who had not been with the family in the shelter. Placements involving the child welfare system were rare at the time homeless families were staying in emergency shelters, but the incidence of such out-of-family placements grew over time. Separation from children while in emergency shelter was associated with additional housing instability in the 20 months following a shelter stay. Finally, additional housing instability following the families initial stay in shelter was associated with child separations as of 20 months later. Policy makers and practitioners should seek to understand parent-child and parent-partner separations and reunifications within families experiencing homelessness. (Author Abstract Modified)