Behavioral observations and sociometric ratings were assessed in separate 3- and 4-year-old child care classes across a two year period. A cross sequential design included three cohorts. Cohort A was observed at age 4, Cohort B at ages 3 and 4 and Cohort C was observed at age 3 yielding two separate cross sectional comparisons and a longitudinal comparison across ages 3 and 4. Social network analyses were used to determine the relation between behavioral measures of social interactions and sociometric ratings, developmental changes in the degree of organization of the social networks in each class, and the degree to which gender was an organizing principle in the social structure of both age groups. In general, correspondence between the behavioral observations and sociometric ratings increased with age and the social structure showed greater cohesion in the 4-year-old class. Gender was an organizing principle in the social structure of the 4-year-old class and became more apparent across time in the 3-year-old class. Implications of the findings for the assessment of sociometric status and for intervention are discussed.