As a matter of constitutional doctrine, the right to keep and bear arms is coming of age. But although the doctrine has begun to mature in the decade since District of Columbia v. Heller, scholars, advocates, and judges disagree about (and sometimes simply do not know) how to characterize it. This Article is the first comprehensive empirical analysis of postHeller Second Amendment doctrine. Beginning with a set of more than one thousand Second Amendment challenges, we have coded every available Second Amendment opinion—state and federal, trial and appellate—from Heller up until February 1, 2016. The dataset is deep as well as broad, including dozens of variables regarding the content of each challenge, not just whether it prevailed. Our findings help provide an objective basis for characterizing Second Amendment doctrine and framing new scholarly inquiries. This is a particularly important task now, as the Amendment becomes a part of “normal” constitutional law and increasingly susceptible to the standard tools of legal analysis.