Drawing on data from the Head Start Family and Child Experiences Survey (FACES), a nationally representative sample of low-income children enrolled in Head Start, this brief examines young children's progress over a two-year enrollment period across three key indicators of school readiness: socio-emotional, cognitive, and health-related outcomes. A cohort of three-year old children was assessed in the fall of 2006, when children entered Head Start, and again in the spring of 2008, when they completed the program. This brief compares children in the cohort who are homeless or highly mobile (HHM) with the cohort's low-income but stably housed children to determine what differences in outcomes, if any, exist between housing groups. (author abstract)