CRISPR systems have been developed, to date, to edit the genes of one type of cell at a time. Now, a new technique has been characterized that can add or modify genes within a community of many different species simultaneously, opening the door to the idea of “community editing.” The system could be used to edit and track — using a barcode — edited microbes within a natural community, such as in the gut or on the roots of a plant where hundreds or thousands of different microbes congregate.