Focusing on readability and interest factors of instructional materials for adult education, the study examined the possible relationships between performance and expressed interest in individual reading passages and in categories of passages. Passages on one of three levels of difficulty were administered to 180 adult education students from three New York State instructional centers. Students then answered multiple choice questions evaluating their comprehension of the materials and rated each selection according to interest level and category interest. Data analysis indicated negative correlations between passage interest and performance at the easy and difficult materials levels and a high positive correlation with moderate material. Positive correlations were indicated between performance and interest by categories for all subjects; categories ranked from most interesting to least interesting were: people, functions of the body, animal life, history, and environment. It appears that the readability leveling may not feature all the factors influencing comprehensibility of material for adults and that low reader groups may be more sensitive to interest by category of material than high reader groups. Further study is needed to examine motivation, material relevancy, and material interest in non-testing situations, as the test conditions of the study may have influenced performance over interest factors. (EA)