The more complex a plant or animal, the more difficulty it should have adapting to changes in the environment. But if that tenet is true, how do you explain all the well-adapted, complex organisms in the world? This “cost of complexity” conundrum puzzles biologists and offers ammunition to proponents of intelligent design. A new analysis reveals flaws in the models from which the cost of complexity idea arose and shows that complexity can, indeed, develop through evolutionary processes.