Despite widespread interest in the impact of patent assertion entities (“PAEs”) on the U.S. patent system, there has been no publicly available dataset that categorizes more than a fraction of lawsuits as involving practicing entities, non-practicing entities (“NPEs”), or PAEs. To address this knowledge gap, Stanford Law School student researchers, led by Mark Lemley and Shawn Miller, have created the Stanford NPE Litigation Dataset (“the Dataset”). The Dataset is the first comprehensive patent litigation dataset to categorize patent asserters and will do so for every U.S. patent lawsuit filed since 2000. With over 80% of total cases categorized as including practicing entities or one of eleven types of NPE patent asserters, the Dataset is nearing completion of the 63,000 lawsuits filed between 2000 and 2017. Thereafter, we will continue to update the Dataset with more recently filed lawsuits. The Dataset provides an invaluable tool to help policy makers craft effective rules, and help judges, litigators, and scholars better understand the nature of the entities filing patent suits. This is especially true because the Dataset captures how patent litigation patterns evolve over an era of heightened activity and policy reform. The Dataset will reveal trends before and after passage of the America Invents Act, key Supreme Court patent cases including eBay and Alice, and various executive orders focused on increasing transparency and reducing costs in patent suits. The first half of this paper explains the motivation for creating the Dataset and details the methodology used to create it. At present, we have completed and made public a random sample of 20% of the lawsuits filed from 2000 through 2015 (10,812 lawsuits). We utilize this sample in the second half of the paper to reveal, for the first time ever, trends in the share of patent disputes attributed to different types of patent asserters over a span of sixteen years. These trends show that while practicing entities dominated patent litigation in the first half of the 2000s, NPEs and PAEs now assert patents in most lawsuits. Further, the trends show that the rise of NPEs and PAEs began before—and thus is not attributable to—the 2011 change in joinder rules. We hope this data will be used to further policy discussions and therefore conclude this paper with examples of how the Dataset can be used in future research on the impact of different types of patent asserters on the patent system.