The relationship between first-grade reading achievement and selected experimental language measures was investigated. The measures selected for study were (1) number of T-units (communication units) spoken in an experimental situation, (2) mean length of T-unit, (3) ratio of subordinate clause length to T-unit length, (4) ratio of sentence-combining transformations to T-units, (5) percent of words at Thorndike-Lorge frequency levels 1 and 2, (6) percent of words at Thorndike-Lorge frequency levels 3-5, and (7) the type-token ratio. Subjects were 60 first-grade pupils from six suburban schools representing three socioeconomic levels. No single language measure nor any combination of these measures was found to have as much value in predicting reading achievement as did the Metropolitan Readiness Test (MRT). Certain combinations of the experimental language measures added significantly to the value of the MRT i n predicting first-grade achievement in both word recognition and comprehension. Mean T-unit length added significantly to the value of the readiness test in predicting comprehension. Other findings and conclusions are offered. Tables and references are included. (Author/CM)