Consciousness might help to mobilize and integrate brain functions that are otherwise separate and independent. Evidence for this ‘conscious access hypothesis' was described almost two decades ago, in a framework called global workspace theory. The theory had little impact at first, for three reasons: because consciousness was controversial; the evidence, though extensive, was indirect; and integrative theory was unfashionable. Recent neuroimaging evidence appears broadly to support the hypothesis, which has implications for perception, learning, working memory, voluntary control, attention and self systems in the brain.