A study of science textbooks and students' responses indicates that many key concepts are treated at different levels of meaning. As a consequence of these observations we have attempted to examine what we have termed students' “preferential thinking style.” To do this, the level of meaning that students preferred when thinking about each of 16 key concept definitions associated with the theme, the nature of matter, was measured for each concept. The same concept definitions had already been studied in respect to students' ability to recognize them. Each of the 16 concept terms was formulated at the three levels of meaning defined by us as: membership, partial association, and generalization. The resulting test of preferential thinking style was administered to representative samples of Hindi-speaking high school students in India (826) and English-speaking high school students in Tasmania (1635). Some marked changes in the relative development of preferential thinking styles for the two groups were observed which raises questions associated with the importance of this notion as an outcome of science teaching.