In the current science education literature, most of the attention has focused on understanding the impact visual representations in textbooks and multimedia materials have on students and their learning, but very few studies have focused on teachers' use of these graphics in the classroom. The purpose of this study is to investigate how seven high school science teachers use visual representations in their teaching. A case study approach was used in this research. First, mini-cases were developed to examine the research question from the participants' perspective; then, a cross-case analysis was used to examine the similarities and differences among participants to develop an overarching case in order to understand the factors involved with teachers' use of visual representations. The findings of this study indicate that course content, student characteristics, and resource availability affect how teachers select and use graphics in their science courses. (Contains 3 tables.)