The Early Communication Indicator (ECI) is a measure relevant to intervention decision making and progress monitoring for infants and toddlers. With increasing recognition of the importance of quality early childhood education and intervention for all children, measurement plays an important role in documenting children's progress and outcomes of early educational experiences. Screening and progress-monitoring measures used in a response-to-intervention approach require age-based benchmarks for decision-making support. The goal of this study was to create a normative sample of ECI data referenced to children served by Early Head Start, including children with Individualized Family Service Plans (IFSPs). In a large sample of children (N = 5,883), program staff in 27 Early Head Start programs in two states collected ECI data from 2002 to 2007. Results indicated that children's ECI total communication growth was conditional on IFSP status but not on gender or home language (English versus Spanish). Children's patterns of communication on the ECI key skill elements (i.e., gestures, vocalizations, single words, and multiple words) were also conditional on IFSP status. Children with IFSPs had (a) later ages of onset for vocalizations, single words, and multiple words; (b) generally slower growth over time; and (c) significantly lower mean levels in the most advanced key skill: multiple words at 36 months of age. Implications for early childhood researchers and service providers are discussed. (Contains 6 notes, 6 tables, and 3 figures.)