Abstract: A principal requirement for students tackling plane geometry problems is to be able to work on the given figure(s) in ways that would help them get closer to the solution. In order to make satisfactory progress at this stage of the solution process, students need to access and use prior geometrical knowledge effectively. The effectiveness with which students are able to utilize their prior knowledge, largely depends on the quality of knowledge that they have developed as a consequence of learning experiences provided by teachers and other agents. In this paper. I draw upon a model of geometry knowledge development and highlight features of geometry knowledge that could assist students handle the early phase of diagram analysis that is critical for further progress in a problem- solving situation. The paper also provides suggestions for improving students’ geometry knowledge base.