Some 2700 Belgian students (grades five through twelve) participated in this study of the relationships between linguistic features of passages and passage readability estimated from cloze procedures. Clozed versions of each of 60 test passages were prepared and administered to students at various grade levels. Twenty-five linguistic features of written style were also identified and scored for each passage. Factor analysis of the 25 linguistic scores yielded a content factor (didactic and descriptive reading versus light reading), a syntactical complexity factor, and a redundancy factor. The three factors together, however, accounted for only 55% of the total variance. Regression analyses indicated that the linguistic features were of varying importance to comprehension at different ages. Semantic content seemed to pose the main difficulty for the youngest children; older children were more able to use additional types of clues (such as repetitions of words) and were more sensitive to syntactic difficulties. (AA)