The National Child Care Staffing Study (NCCSS) was designed to explore how child care teaching staff and their working conditions affect the caliber of center-based child care. Four major policy questions were addressed: (1) Who teaches in America's child care centers? (2) What do they contribute to the quality of care provided? (3) Do centers that meet or fail to meet nationally established quality guidelines, that operate under different financial and legal auspices, and that serve families from different socioeconomic backgrounds also differ in the quality of care offered to children or the work environments offered to their staff? (4) How have center-based child care services changed from 1977 to 1988? Participants were 227 child care centers in 5 metropolitan areas: Atlanta (Georgia), Boston (Massachusetts), Detroit (Michigan), Phoenix (Arizona), and Seattle (Washington). Classroom observation and interviews with center directors and staff provided data on center characteristics and program quality, and on staff qualifications, commitment, and compensation. In Atlanta, child assessments were also conducted to examine the effects on children of such center and staff attributes as program quality and staff training. Part I of this report describes the purpose, goals, and design of the NCCSS. The six chapters of Part II concern child care teachers and the quality of care in America. Part III describes variations across centers. Part IV presents recommendations and a conclusion. Related materials, including 55 references and a glossary, are appended. (author abstract)