According to national standards, eighth graders should possess appropriate understandings regarding groundwater and its role in the hydrologic cycle. This article describes a study of eighth-grade students to determine what types of ideas eighth graders actually possess regarding groundwater. The students completed a survey that consisted of one multiple-choice item and a drawing prompt. The results of this survey, along with videotaped class discussions about goundwater, revealed that students of this age group hold naive conceptions concerning groundwater. In addition, the students spatial reasoning was identified as contributing to their conceptions.