Kieran Egan (1979) has challenged educationists to consider the need for a Theory of Development which is specifically Educational. Such a need is discussed and examined in the context of science teaching. Egan's Theory was applied to the selection of science text material for a group of eleven and twelve year old students. The students' responses to the materials were compared with Egan's descriptions of certain developmental stages, particularly of his Romantic Stage. The author concluded that Egan's theoretical proposition assisted in interpeting certain student behaviour and preferences. Possible classroom uses of Egan's theory are discussed, implications for text usage and design are outlined, and some areas of research are suggested.