This study investigated the impacts of sleep habits, problem behaviors and health status on differential fall-to-spring gains in letter knowledge found in pre-kindergarten children. Four-year-olds attending pre-kindergarten programs who could identify 0–3 letters at school entry in the fall were studied. Two groups were created based on letter knowledge in the spring, one composed of children who continued to only identify 0–3 letters and the other composed of children who correctly identified 4 or more of 15 letters. The two groups of children (24 males, 36 females) were matched on age, general cognitive skills, and gender. Parental reports about the children’s sleep habits, problem behaviors, and health status were obtained using a questionnaire. Scores were used to differentiate group gains in letter knowledge. Children making small gains in letter knowledge were characterized by shorter nighttime sleep duration, multiple problem behaviors that parents regarded as very descriptive of their child, and the presence of more than one chronic health problem.