This study focused on college students' development of conceptual knowledge in geographic information system (GIS). The aim of this study was to examine if and how students developed their conceptual knowledge during their enrollment in an introductory-level GIS course. Twelve undergraduate students constructed 36 concept maps and revised 24 concept maps in three sessions. The author scored those 60 concept maps in two different ways. The first method measured the degree to which concept maps were structurally complex; the second method assessed the correctness of interrelationships between spatial concepts shown in the maps. A statistical analysis of the scores obtained through the second method suggested that there was a significant difference between the maps created in the first session and the maps revised in the second session. Students could successfully revise their original concept maps at the middle of a semester. A mix of the two quantitative and qualitative methods had the potential to examine the development of students' conceptual knowledge through multiple perspectives. Lastly, this study discusses how concept maps can be applied to research and instructions. Concept maps can be used for exploring students' understanding of spatial concepts.