The question whether the Patient Protection and Affordable Care Act (“PPACA”) is “unconstitutional” is thorny, not simply because it presents intriguing issues of interpretation but also because it starkly illustrates the ambiguity that often accompanies the word “unconstitutional.” The term can be, and often is, used to mean a wide range of things, from inconsistency with the Constitution’s text to inconsistency with a set of policy preferences. In this article, we briefly explore the range of meanings that attach to the term “unconstitutional,” as well as the problem of determining the “constitutionality” of a lengthy statute when only some portions of the statute are challenged. We then, using “unconstitutional” to mean” inconsistent with an original social understanding of the Constitution’s text (with a bit of a nod to judicial precedents),” show that the individual mandate in the PPACA is not authorized by the federal taxing power, the federal commerce power, or the Necessary and Proper Clause and is therefore unconstitutional.