The MSHS Study has two components: a Program/Center component and a Classroom, Family, Child component that are based on distinct samples. The first component is off-site and consists of mailed surveys that will be sent to the universe of MSHS program directors and a representative subset of center directors to provide information on program and center operations. The second component consists of onsite data collection - including classroom observations, surveys with teachers and assistant teachers, parent interviews, teacher and parent child reports, and direct child assessments - with a nationally-representative sample of centers, classrooms, families and children.