The validity of several dimensions of knowledge which were inferred from concept maps was assessed for its psychometric and edumetric aspects. Data were collected from 14 students who enrolled in the university first-year introductory geomorphology course and in its prerequisite introductory geology course. They took an objective geomorphology test, the tree construction task, and the Standardized Concept Structuring Analysis Technique (SConSAT) version of concept mapping. Comparisons among these dimensions of knowledge before and after the geomorphology course yielded convergent evidence. For the psychometric perspective, the SConSAT version of concept mapping and tree construction had similar knowledge structure representations, and the cognitive map correctness was moderately positively correlated with the objective test but not with the geomorphology course test. For the edumetric perspective, the majority of the dimensions of knowledge structures from the SConSAT showed large improvements following the geomorphology course. This evidence shows that the knowledge structure dimensions have moderate to good construct validity which warrant their widespread use for evaluating learning outcomes in both experimental and classroom settings. © 1997 John Wiley & Sons, Inc. J Res Sci Teach 34: 925-947, 1997. Concept mapping is widely used in science education research and development. Most of its educational applications aim to describe features of student knowledge, assess it, and detect and characterize structural and substantive changes in this knowledge (namely, learning outcomes) and for instructional purposes (e.g., Horton, McConney, Gallo, Woods, Senn, & Hamelin, 1993;Mason, 1992;Roth & Roychoudhury, 1992, 1994Wallace & Mintzes, 1990;Wandersee, 1990). This interest may be due in part to the fact that concept mapping is consistent with a constructivist perspective of learning when it is used to examine changes in the content and organization of student knowledge by emphasizing the process of the construction and the uniqueness of the individual products (Beyerbach & Smith, 1990;Roth & Roychoudhury, 1992). In this articles we report the assessment of the psychometric and edumetric aspects of the validity of certain dimensions of knowledge derived by concept mapping in the context of a university course in geomorphology. We will review definitions of cognitive structure, outline JOURNAL OF RESEARCH IN SCIENCE TEACHING VOL. 34, NO. 9, PP. 925-947 (1997) © the ideas that underlie construct validation, and describe briefly concept mapping as a probe of cognitive structure. Theoretical FrameworkIn recent decades, educational and psychological researchers came to treat learning outcomes in terms of the relations between the structure of the discipline (content area) and the individual's "cognitive structure" or "knowledge structure" (e.g., Howard, 1987;Nitko, 1989). Some of the definitions for the latter hypothetical construct are (1) a semantic space that is an organization or pattern of the internal...