Three hypotheses gave direction to this study conducted with a stratified random sample of fourth grade students. The chief purpose was exploration of the relationship between a subject's understanding of conjunctions and his reading comprehension. Another purpose was to explore the difference in the difficulty of various conjunctions. The third purpose was related to the relationship between understanding conjunctions and the demographic variables of socioeconomic level, sex, and intelligence. Four tests were administered: Comprehension of Conjunctions, Cloze Comprehension of Conjunctions, Stanford Achievement, and Pintner Mental Ability. The data were analyzed by statistical procedures. Results of the study show (1) there is a significant relationship between reading comprehension and understing conjunctions; (2) nine conjunctions were found significantly difficult, and four were found significantly easy; and (3) girls achieved higher than boys on measures of comprehension of conjunctions, and there was a high positive relationship between socioeconomic level and all measures of comprehension of conjunctions. These findings provide indications for improving instruction of disadvantaged students in the area of reading comprehension, and greater individualization of instruction is suggested. (DB)