Research shows that well trained and educated early child care and education (ECCE) workers are key to helping children in care reach their full developmental potential. Federal and state governments spend billions of dollars each year to improve ECCE programs, including the quality of its caregivers and teachers. Because of the importance of this workforce and the federal investment in it, US Government Accountability Office (GAO) examined (1) what is known about the composition, education, and income of the ECCE workforce and how these characteristics relate to quality, and (2) what activities are the Departments of Health and Human Services (HHS) and Education, and the states financing to improve worker quality? GAO surveyed state child care administrators, interviewed HHS, Department of Education (Education), and other federal and state officials; interviewed ECCE experts and researchers; analyzed Census Bureau and Head Start data; conducted a literature search; and reviewed relevant federal laws and regulations. Appended are: (1) Scope and Methodology; (2) State Workforce Improvement Activities; (3) Cited Studies in the Report; (4) Comments from the Department of Health and Human Services; (5) Comments from the Department of Education; and (6) GAO Contact and Staff Acknowledgments. (Contains 3 tables, 6 figures and 33 footnotes.)