This paper reports findings of a main study and a corollary study designed to clarify the relationship between interpersonal and intrapersonal language by examining the spontaneous classroom interpersonal verbal output of children 4-5 years old in relation to social class and intelligence. The report presents (1) preparation of the data of the main and corollary studies for computer analysis, (2) extensive revision and refinement of the specially designed Functional Category System (a comprehensive instrument covering all verbal statements of the preschooler), and (3) analysis of the results. Findings from the main study support significant relationships between some IQ effects and some social class effects as indicators of linguistic effectiveness (performance). Ethnicity (black, white) was significant only in interaction with some social class effects. Significant sex effects were noted. The corollary study assessed effects of a school readiness program or a child development program and indicated that, in general, no subjects showed significant pre-post changes in IQ. IQ scores of advantaged children (in accord with their initial selection) remained significantly higher than those of children selected from the two Head Start programs. (WY)