Four grade 6 classes in the Auburn Public Schools, Washington, were involved in a sequence of 30-minute lessons (8 weeks) developed by the experimenter to ascertain the effectiveness of direct systematic vocabulary instruction emphasizing prefixes, suffixes, and root words. Some elements of sentence structure, mnemonic devices, and etymology were also used. Subtests of the Metropolitan Achievement Tests: Advanced Battery were used to measure differences in general vocabulary, reading comprehension, and spelling achievements between control groups and experimental groups. The groups exposed to the experimental lessons obtained significantly higher mean scores. The findings suggested that intensive directed vocabulary instruction emphasizing the morphological structure of words can have beneficial results in reading comprehension. Although the required level of significance was not obtained in vocabulary and spelling achievement, the results indicated a need for further study. (Author/LK)