Through interviews with 145 children enrolled in two public schools, this study sought to answer five questions: (1) Do children consider page size, type, and illustration position important in their selection of tradebooks? (2) Are there differences between grades, sexes, and among reading ability groups in their consideration of the importance of these format factors in book selection? (3) As a group, do children exhibit preferences within each format factor: page size, type size, type style, and illustration position? (4) Are there differences between grades, sexes, and among reading ability groups for the format factors under investigation? and (5) What do children give as reasons for preferring the format variation selected? From the findings, the following guidelines for the selection of tradebooks were developed: while books having a variety of page sizes should be available to late primary grade children, the majority of books for late intermediate grade children should contain pages of approximately 5 1/2 inches by 8 1/4 inches; type in books for late primary grade children should be at least 12 point, but preferably larger; the type style should be a simple, clear type style, regardless of serifs or their absence; and illustrations in the middle of the page make undesirable choices. (HOD)