This study assesses the impact of cochlear implantation (CI) on spoken language development in young children with severe-to-profound sensorineural hearing loss (SNHL). The CDaCI investigative team conducted a prospective, longitudinal study involving 188 children who underwent CI before the age of 5 and 97 hearing children of similar ages. The primary outcomes were measures of spoken language comprehension and expression. Results showed that children who received CI demonstrated greater growth in language performance compared to their pre-implantation scores, but their language age remained significantly behind that of their chronological age. Children who were younger at the time of CI and had shorter histories of hearing deficit showed significantly higher rates of language acquisition. Multivariable analyses indicated that greater residual hearing prior to CI, higher ratings of parent-child interactions, and higher socioeconomic status were associated with greater rates of language growth. The study concludes that CI in young children is associated with better spoken language learning, but early implantation is crucial to achieve optimal outcomes. Environmental factors, such as family income and maternal engagement, also significantly influence language development after CI.This study assesses the impact of cochlear implantation (CI) on spoken language development in young children with severe-to-profound sensorineural hearing loss (SNHL). The CDaCI investigative team conducted a prospective, longitudinal study involving 188 children who underwent CI before the age of 5 and 97 hearing children of similar ages. The primary outcomes were measures of spoken language comprehension and expression. Results showed that children who received CI demonstrated greater growth in language performance compared to their pre-implantation scores, but their language age remained significantly behind that of their chronological age. Children who were younger at the time of CI and had shorter histories of hearing deficit showed significantly higher rates of language acquisition. Multivariable analyses indicated that greater residual hearing prior to CI, higher ratings of parent-child interactions, and higher socioeconomic status were associated with greater rates of language growth. The study concludes that CI in young children is associated with better spoken language learning, but early implantation is crucial to achieve optimal outcomes. Environmental factors, such as family income and maternal engagement, also significantly influence language development after CI.