Recent advances in noninvasive neuroimaging have set the stage for the systematic exploration of human brain circuits in health and disease. The Human Connectome Project (HCP) is systematically characterizing brain circuitry, its variability, and its relation to behavior in a population of 1,200 healthy adults (twins and their non-twin siblings). This talk reviews the progress by the HCP consortium in acquiring, analyzing, and freely sharing these massive and highly informative datasets. The HCP obtains information about structural and functional connectivity using diffusion MRI and resting-state fMRI, respectively. Additional modalities include task-evoked fMRI and MEG, plus extensive behavioral testing and genotyping. Each of these methods is powerful, yet faces significant technical limitations that are important to characterize and be mindful of when interpreting neuroimaging data. Advanced visualization and analysis methods developed by the HCP enable characterization of brain circuits in individuals and group averages at high spatial resolution and at the level of functionally distinct brain parcels and brain networks. Comparisons across subjects are beginning to reveal aspects of brain circuitry that are heritable or are related to particular behavioral capacities. Data from the HCP is being made freely available to the neuroscience community via a user-friendly informatics platform. Altogether, the HCP is providing invaluable information about the healthy human brain and its variability.