Instruction in one eighth-grade history teacher's classes varied between use and nonuse of vocabulary recognition materials for difficult words to study the possible effect of such materials on test scores. The vocabulary recognition materials were used to augment four chapters of the history textbook that the students studied, while four chapters not accompanied by vocabulary materials served as control chapters, and one chapter was not used in the research at all. Eighty students took all of the tests for chapters in the research design, and their test scores for the experimental chapters were compared to the test scores for the control chapters. Not only were there higher grades for chapters with vocabulary materials, but t-score computations of the overall differences between experimental and control chapters were significant at the .01 level of confidence. The conclusion that vocabulary recognition helps to improve content reading implies that teachers should investigate the reading levels of students and the textbook, followed by attempts to reconcile reading level differences through an emphasis on the difficult vocabulary within the text. (RL)