Abstract Introduction Sleep and the development of language are prominent concerns of many parents and until recently, many have examined these concerns tangentially. Children with developmental delays/disabilities have shown to have impaired sleep and poor sleep quality, and impairments or changes in sleep quality may play a prominent role in the acquisition of language and neuronal oscillatory patterns. This study examines the role of child sleep quality paired with a normed measure of language and wake electroencephalography (EEG). Examining the role of child sleep quality with language ability and wake EEG may provide nascent incremental utility to understanding the influences of sleep on healthy development. Methods Data from 109 toddlers (age range 24 to 30.5 m, M = 26.83 ± 1.58 m, 52% male) from the Brief Infant Sleep Questionnaire (BISQ), Mullen Scales of Early Learning (MSEL), and continuous EEG were collected and analyzed. EEG was recorded (32 electrode cap BioSemi) while toddlers sat in a booster seat and watched a silent video. Data were analyzed in RStudio and Matlab to examine toddler’s sleep quality (infant sleep and parent behaviors) and relations with the MSEL and EEG (controlling for child age and gender). Results Means and standard deviations appeared within expected limits based on the range of each variable. Toddlers with slow-developing language were associated with relatively poor sleep quality, explaining 9.75% of the variance. We find preliminary evidence to suggest a potential sleep disruption around the time when a child is undergoing a rapid expansion in their vocabulary (expressive language). Toddler’s sleep quality and language acquisition were also correlated with wake EEG (alpha and beta). Conclusion Sleep is regarded as an essential component supporting the myriad changes observed in early development. Sleep quality fundamentally influences healthy development across domains. Here, we showed child sleep quality is highly associated with toddler’s language ability, and wake EEG, providing new insights into the developing brain. Support National Institutes of Health R01DC016273, R01MH107652-03S1, and Johnson & Johnson Consumer Inc., Skillman, NJ, USA.