That similar words can prime one another is not news. However, this phenomenon can be exploited to make inferences about the organization of conceptual representations. What types of similarity matter? Although there is evidence that similarity of function, shape, and even manner of manipulation is reflected in semantic memory, evidence for organization on the basis of color similarity is sparse. This lack of evidence is surprising: Intuition suggests that color is a prominent feature of many object concepts. The research reported here clarifies this puzzle and illustrates the dynamic nature of conceptual representations. Our research demonstrates color-based priming (e.g., "emerald" primes "cucumber") in participants who completed a Stroop color-naming task before a priming task. Notably, the size of the Stroop effect predicted the size of the priming effect. When the order of tasks was reversed, priming effects were eliminated. By demonstrating that both extrinsic and intrinsic factors can influence conceptual activation, our findings have implications for theories of semantic memory.