Driven in part by research findings in early childhood development, the academic, business, and policy communities now recognize that high-quality preschool programs are an important way to help children reach their full potential. Although some current research suggests that teacher preparation at the four-year college degree level is the best way to achieve such quality, recommending such a standard for teachers in early childhood settings has raised considerable debate. This paper reviews research literature on the relationship between teacher preparation and child outcomes in ECE programs, focusing on the central question of whether teachers with at least a BA degree in ECE provide better quality preschool experiences for 3- to 5-year-olds than those with less education. The review was limited to peer-reviewed journal articles and reports, to studies examining education and care programs with classrooms serving 3- to 5-year-olds, and to studies that allowed for exploration of particular features of high-quality programs. The review concentrated on studies with samples including more settings in diverse regulatory environments, and those employing multivariate analyses exploring the relative contribution of teacher education/training to positive program quality and child development. The review notes that although the studies had some limitations in sample, measures, and analytic methods, they underscore the importance of more higher education and specialized training, and identify the role of the bachelor's degree, most often in ECE, in producing teacher behaviors consistent with high-quality programming, which in turn supports better developmental outcomes. The body of research raises several questions requiring further investigation, particularly regarding thresholds of education and training; the content, format, and quality of specialized early childhood training; variations in strategies for teachers with varying characteristics and needs; and the aspects of the adult work environment that scaffold teachers' knowledge, enabling them to engage in effective strategies with children. The review also points out that decisions about qualifications and requirements for preschool and other early childhood teachers will be driven by their feasibility as well as empirical evidence, and that the more diverse a state's preschool system, the more complex it will be to enforce common standards for professional development. (Contains 94 references.) (KB)