In order to better understand the neuropsychological underpinnings of the relative strength in word identification in individuals with Down syndrome, the performance of children and adolescents with Down syndrome (N=29) was compared to the performance of a nonverbal-IQ matched group of children and adolescents with developmental disabilities of mixed etiologies (N=20) on measures letter/word identification and cognitive-linguistic functioning. Though no between-group differences were observed for letter/word identification or visual processing performance, individuals with Down syndrome showed significantly poorer verbal short-term memory and receptive vocabulary skills. In terms of neuropsychological correlates of letter/word identification, significant linear associations were observed between letter/word identification (K-ABC reading/decoding) and verbal short-term memory (K-ABC number recall), as well as receptive vocabulary (PPVT-III) and visual processing (MVPT-R) in both groups. However, when only children with word identification competence (as opposed to letter identification competence) were included in analyses, visual perception scores (total MVPT-R) were significantly associated with word identification in the Down syndrome group, but not in the mixed comparison group. Implications for etiology-specific instructional approaches are discussed.