ABSTRACT Purpose To verify indicators of cognitive development, receptive language skills and adaptive behavioral patterns in toddlers with Williams syndrome (WS). Methods The sample comprised 8 children of both sex, aged between 48 and 72 months with WS. Instruments of data collection were Denver Developmental Screening Test II; Peabody Picture Vocabulary Test; Vineland Adaptive Behavior Scale; Child Behavior Checklist for Ages 1½-5and 6 to 18; Columbia Mental Maturity Scale (CMMS), and Behavior Problems Inventory-01. Results The major developmental impairments were associated with fine motor skills and personal care abilities. Deficits in receptive language and communication skills were reported according to the PPVT and Denver II, respectively. The caregivers reported behavioral and emotional problems associated to anxiety and depression, and attention problems scales of CBCL. Conclusion The toddlers demonstrated deficits in adaptive functioning and behavioral, motor and cognitive difficulties such as inattention and hyperactivity, stereotypies and aggressive behavior.