Public support for and government investments in early childhood education (ECE) are at an all-time high. Research has identified early childhood as a critical period for brain development, work that has spurred interest in expanding ECE programs across the United States. But not all programs produce positive effects at the end of the preschool year. For those that do improve children's outcomes, impacts tend to diminish as children enter kindergarten and elementary school. To maximize these significant investments in ECE, programming must be high quality, brought to scale, and generate substantial impacts on children's early learning that can be sustained through elementary school and into adulthood. As the federal and state governments increasingly invest in ECE programs to improve their quality, MDRC is leading several studies that conceive and measure the quality of ECE classrooms in new and innovative ways. In particular, MDRC is focusing on "instructional quality" by examining promising instructional practices, such as the use of rich content and individualized activity settings and the promotion of higher-order skills within a broad range of learning domains. In doing so, MDRC aims to improve the understanding of the critical aspects of instructional quality that promote school readiness among low-income children and their sustained academic success as they move through elementary school and beyond.