Mathematics education has risen to the top of the national policy agenda as part of the need to improve the technical and scientific literacy of the American public. The new demands of international competition in the 21st century require a workforce that is competent in and comfortable with mathematics. There is particular concern about the chronically low mathematics and science performance of economically disadvantaged students and the lack of diversity in the science and technical workforce. Particularly alarming is that such disparities exist in the earliest years of schooling and even before school entry. Recognizing the increasing importance of mathematics and encouraged by a decade of success in improving early literacy, the Mathematical Sciences Education Board of the Center for Education at the National Research Council established the Committee on Early Childhood Mathematics. The committee was charged with examining existing research in order to develop appropriate mathematics learning objectives for preschool children; providing evidence-based insights related to curriculum, instruction, and teacher education for achieving these learning objectives; and determining the implications of these findings for policy, practice, and future research.