Abstract: The Supreme Court has said that there is a constitutional "right to marry"; but what can this possibly mean? People do not have a right to marry their dog, their aunt, June 29, a rose petal, their neighbors, or a sunny day. This essay attempts to make some progress in understanding both the content and the scope of the right to marry. With respect to content, it concludes that people have no more and no less than this: a right of access to whatever expressive and material benefits the state now provides for the institution of marriage. It follows that the right to marry falls within the "fundamental" rights branch of equal protection doctrine, and is not properly understood in terms of substantive due process; it also follows that the state could abolish the official institution of marriage tomorrow. With respect to scope, the essay identifies a minimal understanding, to the effect that the right to marry is enjoyed by any couple consisting of one adult man and one adult woman. The minimal understanding can claim a plausible defense in a tradition-based understanding of fundamental rights; and on institutional grounds, a tradition-based understanding has a great deal of appeal. Its problem is that it has a degree of arbitrariness. This is a formidable problem, but for reasons of prudence, federal courts should not adopt a broader understanding that would, for example, require same-sex marriages to be recognized. The essay concludes with some remarks on the possible abolition of the official institution of marriage. It explains that there are plausible grounds for objecting to that institution and that there is a real question whether the current system would be chosen if a society were starting from scratch. It emphasizes that marriage is emphatically an government-run licensing system, embodying a set of governmental mandates and conditions. An understanding of this point should inform constitutional discussion, which ought not to proceed by identifying religious and official marriage, or by pretending that the official institution is in some sense natural and foreordained.