This study evaluated effects of a year-long intensive vocabulary program on the reading achievement of 12th-grade college-preparatory English students. A control class followed the regular course of study, and an experimental class supplemented it with completion of the "Harbrace Vocabulary Workshop" workbook, study of the use of footnotes and the literature anthology glossary, the use of newly-learned words in written composition, a critical study of language in Hardy's "The Return of the Native," and oral interpretations of individual poetry and prose. Pre-treatment standardized reading comprehension tests and I.Q. tests indicated the classes were comparable. The "Iowa Test of Educational Development" was given two-thirds of the way through the program, and the "Cooperative English Reading Comprehension Test, Form Z" was used as the post-test. Results revealed no statistically significant differences between the two groups on any of the reading sub-tests, except vocabulary; in reading speed, the control group exceeded the progress of the experimental group. Results indicated that increased maturity and enriched background were relatively more important determinates in most reading skills than vocabulary training. (LH)