Background: Research has shown that the cochlear implant may improve deaf children's speech and communication skills. However, little is known about its effect on children's ability to socialize with hearing peers. Methods: Using a standardized psychological measure completed by parents and a longitudinal design, this study examined the development of communication, socialization, and daily living skills of children who used hearing aids or cochlear implants for an average of 11 and 6 years, respectively. Results: Results show that children with cochlear implants, who were more delayed than children with hearing aids at the outset, made significant progress over time. Children with both devices achieved age-appropriate development after years of hearing aid or cochlear implant use. Conclusions: The pattern of results suggests that cochlear implants may be effective in improving deaf children's communication and social skills.