A study examined the relationship between reading and writing and the abstract thinking ability of college freshmen. It was hypothesized that (1) reading ability, writing ability, and thinking ability would be highly correlated; (2) instruction that improves either reading or writing would also improve thinking; and (3) reading, writing, and thinking skills would all be strong predictors of success in freshman composition. Subjects, 250 freshman composition students at an Oklahoma university, completed the "Test of Everyday Writing Skills" (TEWS), the "Nelson-Denny Reading Test" and the "Watson-Glaser Critical Thinking Appraisal." Of these subjects, 120 were then randomly assigned to three treatment groups--one attending the reading laboratory for 20 sessions, one attending the writing laboratory for 20 sessions, and one making up a control group, attending only the composition class. Only nine subjects completed this second part of the experiment. At the end of the 10-week treatment, subjects repeated the three tests. Final course grades were obtained and discriminant analysis was done using the three test scores. Results indicated that reading ability was better than writing ability as a predictor of thinking ability, but both reading and writing were significantly correlated with thinking and with each other. Age was not a factor in thinking. (Tables of findings are included.) (HTH)