Does Big Data represent an existential threat to CIOs? Yes, quite possibly. For the past three decades, corporate CIOs have served primarily as stewards and guardians of IT infrastructure. Big Data—together with cloud, social and mobile computing—throws the value of legacy IT infrastructure into question and undermines the traditional authority of CIOs over the systems they have championed. For corporate CIOs, getting comfortable with Big Data will require reaching beyond the traditional comfort zone of IT and learning a new language that combines business, math and behavioral science, with significantly less emphasis on traditional infrastructure technology than in the past. Will CIOs be ready and willing to make the leap?