This report examines the scope of the Second Amendment, as interpreted by the federal circuit courts of appeals, after the watershed Supreme Court decisions in District of Columbia v. Heller and McDonald v. City of Chicago. The Second Amendment states that "[a] well-regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear arms, shall not be infringed." Before the Supreme Court's 2008 opinion in Heller, the Second Amendment had received little Supreme Court attention and had been largely interpreted, at least by the lower federal courts, to be intertwined with military or militia use. Still, there had been ample debate in the lower federal courts and political discussion over whether the Second Amendment provides an individual right to keep and bear arms, versus a collective right belonging to the states to maintain militias, with the vast majority of the lower federal courts embracing the collective right theory. In Heller, though, the Supreme Court adopted the individual right theory, holding that the Second Amendment protects an individual right for law-abiding citizens to keep and bear arms for lawful purposes including, most notably, self-defense in the home. Two years later in McDonald, the Court held that the Second Amendment applies to the states via selective incorporation through the Fourteenth Amendment. After Heller and McDonald, numerous challenges were brought on Second Amendment grounds to various federal, state, and local firearm laws and regulations. Because Heller neither purported to define the full scope of the Second Amendment, nor suggested a standard of review for evaluating Second Amendment claims, the lower federal courts have been tasked with doing so in the Second Amendment challenges brought before them. As will be discussed in this report, these challenges include allegations that provisions of the Gun Control Act of 1968, as amended, as well as various state and local firearm laws (e.g., assault weapon bans, concealed carry regulations, firearm licensing schemes) are unconstitutional. Generally, the courts have adopted a two-step framework for evaluating Second Amendment challenges. First, courts ask whether the regulated person, firearm, or place comes within the scope of the Second Amendment's protections. If not, the law does not implicate the Second Amendment. But if so, the court next employs the appropriate level of judicial scrutiny-rational basis, intermediate, or strict scrutiny-to assess whether the law passes constitutional muster. In deciding what level of scrutiny is warranted, courts generally ask whether the challenged law burdens core Second Amendment conduct, like the ability to use a firearm for self-defense in the home. If a law substantially burdens core Second Amendment activity, courts typically will apply strict scrutiny. Otherwise, courts generally will apply intermediate scrutiny. Most challenged laws have been reviewed for intermediate scrutiny, where a court asks whether a law is substantially related to an important governmental interest. And typically, the viability of a firearm restriction will depend on what evidence the government puts forth to justify the law. Yet sometimes courts take a different or modified approach from that described above and ask whether a challenged regulation falls within a category deemed "presumptively lawful" by Heller. If the law falls within such a category, a court does not need to apply a particular level of scrutiny in reviewing the restriction because the law does not facially violate the Second Amendment. The body of this report discusses in detail notable post-Heller Second Amendment cases decided by federal courts of appeals. Because Heller and McDonald provide the only recent Supreme Court guidance on the Second Amendment, the analyses in these cases may provide useful guideposts for Congress should it seek to enact further firearm regulations.