Biologists are posting unreviewed papers in record numbers. Here's a survival guide. In the past 4 years, a movement has begun sweeping across the life sciences: the practice of sharing draft papers, known as preprints, online before they are submitted to a journal for peer review. The shift has been catalyzed, in part, by endorsements from high-profile scientists, as well as the 2013 launch of the bioRxiv preprint server by Cold Spring Harbor Laboratory in New York; it now holds more than 15,000 papers. But in contrast to physics, where preprints took off nearly 3 decades ago without much fanfare or controversy, the leap into preprints is stirring strong passions in the hypercompetitive world of the life sciences. Proponents argue that preprints will accelerate the pace of science—and improve its quality—by publicizing findings long before they reach journals. Many biologists remain wary, however. For those debating whether to take the plunge, Science offers this guide.