The theory of plate tectonics is the conceptual model through which most dynamic processes on Earth are understood. A solid understanding of the basic tenets of this theory is crucial in developing a scientifically literate public and future geoscientists. The size of plates and scale of tectonic processes are inherently unobservable, necessitating the use of images and models in instruction. To explore plate tectonics conceptions held by undergraduates, we designed and administered a postinstruction survey instrument centered on a common schematic representation of plate tectonics. We report results from a sample of n = 60 nongeoscience majors enrolled in five different introductory Earth-science courses taught at a major research university and a community college. Students held a number of alternative conceptions associated with terminology, plate motion, and plate-related subsurface melting. We also note that some aspects of figures commonly used to teach plate tectonics are problematic for students and may actually result in reinforcement of alternative conceptions. Further work at both the K-12 and college levels directed at innovative approaches to address student conceptions regarding plate tectonics, including designing images that support key scientific messages, is needed. This research can inform curriculum development for entry-level geoscience courses as well as the use of images to convey complex science.