This study investigated the relationship between sex-typing of reading and reading comprehension achievement in third grade boys, and sex-typing of reading and reading choice behavior in kindergarten boys. The study also explored the effects of sex and interest of test materials on reading comprehension achievement in third graders. Data were collected on 109 third grade boys, 104 third grade girls, and 3 kindergarten boys. Sex-typing of reading data were collected with an instrument consisting of 15 slides depicting materials related to the subject-matter areas of math, reading, and science. Interest data were obtained with a pencil-and-paper interest questionnaire. Reading comprehension data were obtained with two cloze tests of five paragraphs each, one containing materials of high interest to the student and one containing materials of low interest to the student. A significant sex difference in reading comprehension achievement was found. Sex-typing of reading was found to be significantly related to reading comprehension achievement in third grade boys, and this relationship was significantly stronger with the high interest materials than with the low interest materials. (Author/WR)