Between 1872 and 1890, William James developed an evolutionary account of phenomenal consciousness. He contended that consciousness enables the active evaluation of what is in (or might be in) one’s environment. James hypothesized that this evaluative capacity was selected (in the Darwinian sense) because it regulated the behavior of vertebrates with highly articulated brains. His hypothesis was intended to explain some surprising results in physiology, particularly a series of experiments purporting to show purposive behavior in (of all things) decapitated frogs. This chapter reconstructs and evaluates James’s evolutionary hypothesis, showing how it would explain those surprising experiments. His account requires interactionist dualism, so he also developed what would become an influential objection to epiphenomenalism: that the latter cannot explain the evolution of our natively patterned, phenomenal pleasures and pains.