Proficiency in social interaction with adults and peers is an important outcome in early childhood. The development of an experimental measure for assessing growth in social skills in children birth to 3 years is described. Based on the general outcome measurement (GOM) approach (e.g., Deno, 1997), the measure is intended for use by early intervention practitioners to identify children having difficulty acquiring social interaction skills and to monitor children's progress during the course of interventions. Results from a sample of 57 infants and toddlers demonstrated the feasibility of 1 of 14 possible measures, positive verbal social behavior (PVSB), in terms of its sensitivity to growth over time, psychometric properties, and practicality for use by early interventionists. Implications for future research and practice are discussed.