Concept mapping typically refers to the graphic representation of concepts and their interrelationships. In this instance, concept mapping is used as a means for assessing an individual's conceptual understanding of a curricular topic. In a series of studies with teacher trainees, emphasis was on determining whether concept maps have regular features which are quantifiable and which change as a function of instruction. Differences were found on number of items (differentiation) on pre and post maps for topics which were the focus of course instruction but not for topics for which there was not instruction. The internal contents of maps were highly idiosyncratic and, although in the absence of instruction, there were not significant changes in differentiation or overall complexity, there were changes in the specific content included. Nevertheless, the maps appeared to be excellent diagnostic devices for determining individuals' conceptions regarding topics such as "teaching,""classroom management,""documentation of children's gains." Differences were also found on differentiation scores and on the number of subordinate levels portrayed between groups of teacher trainees with differing amounts of education for the topic "teaching." Years of experience for inservice teachers, however, were not related to scores derived from maps. (Author)