Children's high and increasing levels of screen time are of growing concern to parents, health professionals, and researchers. With the growing availability and use of devices such as smartphones and tablets, it is important to understand the impact of children's screen use on development. Prospective longitudinal data from 6,281 children (48.3% female) in the Growing Up in New Zealand study were used to examine relations between the extent of screen exposure in early childhood (2-4.5 years) and later language development, early educational skills, and peer social functioning at ages 4.5 and 8 years. Higher levels of screen exposure were associated with lower levels of vocabulary, communication, writing, numeracy, and letter fluency and higher levels of peer problems. These associations were reduced after controlling for confounding family social background factors but remained significant. Results indicate that more than 1.5 hr of daily direct screen time at age 2 was associated with below average language and educational ability and above average levels of peer relationship problems at age 4.5. Exposure to more than 2.5 hr of daily direct screen time was associated with higher than average peer relationship problems at age 8. Findings indicate that high levels of screen exposure during early childhood are negatively associated with children's later language, educational, and social development. Such information is critical to help inform policy guidelines, health care, and parenting practices regarding the availability and children's use of screens in early childhood. (PsycInfo Database Record (c) 2025 APA, all rights reserved).