When individuals replace their naïve theories of natural phenomena with more accurate, scientific ones, what happens to the original theories? Are they overwritten or merely suppressed? We investigated this issue by asking college undergraduates to verify two types of statements as quickly as possible: statements whose truth value was the same across naïve and scientific theories of the phenomena at hand (e.g., “The moon revolves around the Earth”) and statements whose truth value differed across those theories (e.g., “The sun revolves around the Earth”). Participants verified the former more quickly and more accurately than the latter, though this difference was smaller for early-developing domains (fractions, germs, inheritance, matter, physiology) than late-developing domains (astronomy, evolution, mechanics, thermodynamics, waves). These findings suggest that intuitive theories survive the acquisition of a mutually incompatible scientific theory, coexisting with, or even competing with, that theory for many years to come.