How do we make difficult decisions, inhibit inappropriate behaviors, or switch between different cognitive tasks? These capabilities are facilitated by so-called "cognitive control", which is driven by a few very specific regions of the human brain. While the anatomical locations of these regions are known, exactly how these regions enable cognitive control is far from understood. In this talk, I will posit that network control is a fundamental mechanism of cognitive control. I will develop, apply, and test structural controllability theory in the context of images of the brain acquired non-invasively in healthy adults. These studies demonstrate that the exact location of regions within the brain's structural wiring explain their unique roles in cognitive function. I will close by discussing the potential applications of this new knowledge in the context of clinical interventions in people with neurological disease and psychiatric disorders.