This study presents a quantitative method for scoring concept maps generated by students learning introductory college chemistry. Concept maps measure the amount of chemical information the student possesses, reasoning ability in chemistry, and specific misconceptions about introductory and physical chemistry concepts. They provide a visualization of cognitive structure. When a student draws a concept map for chemical reactions, the result is a model of the student's conceptual framework for understanding the concepts and propositions of chemical change. Developing a valid method for scoring student concept maps will enable educators to evaluate student knowledge free of the bias and arbitrariness often associated with qualitative reviews. Concept maps may be evaluated quantitatively by categories. The category score for propositional validity reflects student reasoning ability in chemistry. The score significantly correlates with formal reasoning ability in chemistry. The category score for hierarchical structure reflects the amount of chemical information possessed by a student. Students who possess large amounts of information about chemistry, position more vocabulary words within each hierarchical level than the student who demonstrates limited chemical knowledge. It is suggested that the greater a student's understanding of introductory chemistry concepts the more strands are employed in mapping concepts and propositions related to chemical reactions. Low strand count reflected specific misconceptions about Avogadro's Number, the mole concept, and the Law of Conservation of Matter. (Author/MM)