In recent years, the Supreme Court has increasingly made “reasonableness” the central inquiry of whether a search or seizure is constitutional under the Fourth Amendment. The rise of the reasonableness approach has coincided with originalist scholarship that claims this interpretation is more consistent with the Amendment’s text and history. This Note looks at Framing-era search-and-seizure practice and argues that the Court’s modern reasonableness interpretation is, in fact, ahistorical and inconsistent with Framing-era practice and the Amendment’s original understanding. Not only is there scant evidence that the legality of searches and seizures turned on their reasonableness during the Framing era, but the arguments made in favor of the Court’s modern reasonableness approach are based on flawed historical assumptions. As a result, the Court’s various applications of its reasonableness interpretation are all inconsistent with Framing-era practice and the Amendment’s original understanding.