To decide whether and where to move in the body, cells must read chemical signals in their environment. Individual cells do not act alone during this process, two new studies on mouse mammary tissue show. Instead, the cells make decisions collectively after exchanging information about the chemical messages they are receiving. “Cells talk to nearby cells and compare notes before they make a move,” says Ilya Nemenman, a theoretical biophysicist at Emory University and a co-author of both studies, published by the Proceedings of the National Academy of Sciences (PNAS). The co-authors also include scientists from Johns Hopkins, Yale and Purdue. David Ellison, Andrew Mugler, Matthew D. Brennan, Sung Hoon Lee, Robert J. Huebner, Eliah R. Shamir, Laura A. Woo, Joseph Kim, Patrick Amar, Ilya Nemenman, Andrew J. Ewald, and Andre Levchenko. Cell–cell communication enhances the capacity of cell ensembles to sense shallow gradients during morphogenesis. PNAS, January 2016 DOI: 10.1073/pnas.1516503113 Andrew Mugler, Andre Levchenko, and Ilya Nemenman. Limits to the precision of gradient sensing with spatial communication and temporal integration. PNAS, January 2016 DOI: 10.1073/pnas.1509597112