This yearlong study was implemented in seventh-grade life science classes with the students' regular teacher serving as teacher/researcher. In the study, a method of scoring concept maps was developed to assess knowledge and comprehension levels of science achievement. By linking scoring of concept maps to instructional objectives, scores were based upon the correctness of propositions. High correlations between the concept map scores and unit multiple choice tests provided strong evidence of the content validity of the map scores. Similarly, correlations between map scores and state criterion-referenced and national norm-referenced standardized tests were indicators of high concurrent validity. The approach to concept map scoring in the study represents a distinct departure from traditional methods that focus on characteristics such as hierarchy and branching. A large body of research has demonstrated the utility of such methods in the assessment of higher-level learning outcomes. The results of the study suggest that a concept map might be used in assessing declarative and procedural knowledge, both of which have a place in the science classroom. One important implication of these results is that science curriculum and its corresponding assessment need not be dichotomized into knowledge/comprehension versus higher-order outcomes.