This Essay develops the idea that there is a practice called constitutional hardball. The practice has three characteristics: it involves arguments and behavior by political actors (including judges, although their role is less interesting than that of other political actors) that are defensible - though sometimes only barely so - by standard constitutional doctrine; it is inconsistent with settled pre-constitutional understandings; and it involves extremely high stakes (control over the national government as a whole). I argue that constitutional hardball occurs when political actors see the chance for a permanent transformation of the constitutional order. I offer a number of illustrations from constitutional history and contemporary controversies. Although the Essay is largely descriptive, I conclude with some modest normative observations about whether constitutional hardball is healthy for a constitutional community and, for those who think it is not, how we can avoid the practice.