This investigation seeks to confirm a computer-based approach that can be used to score concept maps (Poindexter & Clariana, 2004) and then describes the concurrent criterion-related validity of these scores. Participants enrolled in two graduate courses (n=24) were asked to read about and research online the structure and function of the heart and circulatory system, to construct a concept map, and then to write a 250-word essay on this topic. Pathfinder and Latent Semantic Analysis approaches were used to analyze the data. Term agreement with an expert was significantly related to human-rater concept map scores (r 0.75). All of the computer-derived scores were significantly correlated to human-rater essay scores (maximum r = 0.83). These results indicate that automatically derived concept map scores can provide a relatively low-cost, easy to use, and easy to interpret measure of students' science content knowledge. (Contains 1 chart.)