Much evidence suggests that, early in life, auditory input and communication are essential for the normal development of language, cognition, and behavior. Thus, deaf children, who experience significant disruptions in auditory input, are likely to show delays not only in the production of oral language but in other important aspects of development such as visual attention and behavioral control. Cochlear implants have shown tremendous promise in restoring auditory information to deaf children and concomitant improvements in speech recognition and production. However, little is known about how cochlear implants affect psychological variables. In this multisite trial, we assess the effects of cochlear implants on a range of developmental outcomes, including visual attention, problem-solving skills, symbolic play, and social adjustment. Measuring these constructs in young children, primarily younger than 2 years, has presented a number of unique challenges. In this article, we describe the methods used to assess these variables in young children and present preliminary findings comparing joint attention and symbolic play skills in a small sample of age-matched deaf and hearing children. As expected, deaf children performed more poorly than hearing children on measures of attention and symbolic play. As auditory input is restored via a cochlear implant, we predict that significant improvements in these variables will be observed.