There is a critical need to establish cost effective ways to monitor developmental progress of children at risk for developmental disabilities. The Vineland Adaptive Behavior Scale (VABS) is a well-known functional measure used for both clinical and research purposes. The objective of this study was to examine the equivalence reliability of the VABS using two different administration methods; in-person versus telephone interviews. Fifty children with or at-risk for developmental disability were tested (mean age of 77.5 +/- 18.5 months) using both interview formats. Correlations between in-person and telephone interview scores were extremely high for all subdomains including Communication (ICC = 0.99), Daily Living Skills (ICC = 0.98), Socialization (ICC = 0.96), Motor (ICC = 0.98) as well as the Adaptive Behavior Composite score (ICC = 0.99). The ability to collect reliable information on a child's developmental progress using a telephone interview format is critical, given current service delivery constraints.