This study describes the function of illustration in the books written by Maurice Sendak and Mercer Mayer. Fifty children between the ages of four and six years old, together with a parent, listened to two books by each author, during three storytime sessions. Children's spontaneous responses to the readings were recorded on videotape. Response was defined as the comments and gestures children made in regard to the readings. Two identical 10-question surveys, one for the books by Sendak and one for the books by Mayer, were administered to parents and children after the storytime session. Responses collected from the data included: likes/dislikes of stories and pictures, scariness of stories and pictures, mood, content of favorite story, and importance of illustrations in understanding the stories better. Results indicated that 98% of the 50 participants liked the stories by Mayer and 86% liked those of Sendak. Participants also liked the pictures, and the stories and the pictures did not scare them. "Happy" and "good" were the predominant feelings generated by the pictures in all four stories. Overall, children liked best Sendak's "Where the Wild Things Are" (78%). Responses tabulated from parents suggested that illustration is necessary and helpful to better understand a story. (Contains 28 references and 6 tables of data. Two survey instruments are attached.) (Author/RS)