This report examines the interrelations among several verbalization indexes on a sample of 27-month-old children and the relation of this data to vocalization scores obtained in the first year. Subjects, 67 girls and 75 boys, were firstborn Caucasian children observed at 4, 8, 13, and 27 months. Parent education varied from incomplete high school to graduate degrees. The evaluation at 27 months included a 2 hour laboratory visit where children received verbalization scores on free play, narrated visual scenes, human forms, and clay faces. Within two weeks, through 6-8 hours of home observation, speech quality and quantity were rated. At 4 and 8 months of age, subjects were shown slides of four male faces, and the clay faces used at 27 months. At 13 months they saw the human forms and clay faces used at 27 months. Total time vocalizing was the variable of interest. The major results suggest (a) greater interepisode consistency for spontaneous verbalization at 27 months for girls than for boys, (b) a stronger covariation between parental educational level and vocabulary score among girls than boys, and (c) greater predictive stability of spontaneous vocalization at 1 year to spontaneous verbalization at 27 months for girls than for boys. These data suggest that the tendency to vocalize is a more stable response tendency for girls than for boys. (Author/JF)