Positioning based on visible light is gaining significant attention. But most existing studies rely on a key requirement: The object of interest needs to carry an optical receiver (camera or photodiode). We remove this requirement and investigate the possibility of achieving accurate positioning in a passive manner—that is, without requiring objects to carry any optical receiver. To achieve this goal, we propose PassiveVLP, in which we exploit the reflective surfaces of objects and the unique propagation properties of LED luminaires. We present geometric models, a testbed implementation, and empirical evaluations to showcase the opportunities and challenges posed by this new type of passive positioning. Overall, we show that our PassiveVLP can track with high accuracy (a few centimeters) a subset of an object’s trajectory, and it can also identify passively the object’s ID.@en