When scientists try to model human brain diseases using other organisms, whether they are truly pinpointing the cellular roots of these diseases in humans is always a question. Now, in a package of 21 research studies across Science (October 13 issue), Science Advances (October 13 issue), and Science Translational Medicine (October 12), researchers present a resource that can help – an atlas of the human and non-human primate brain at the cell-type level, in unprecedented detail. The researchers’ collective efforts characterized more than 3,000 human brain cell types, revealing features that distinguish us from other primates in some. Understanding the human brain at such resolution will not only help scientists pin down which cell types are most affected by specific mutations, leading to neurological diseases – it will also offer new understanding of who we are as a species. The studies in this package are part of the National Institutes of Health’s BRAIN Initiative Cell Census Network (BICCN), a program launched in 2017. As part of this effort, hundreds of scientists collaborated on a range of studies, leveraging the most advanced technologies of molecular biology.