Coalitions are often condemned as undemocratic and unprincipled because of the compromises they involve. Politicians are accused of betraying the commitments they made during the election. Paradoxically, proponents of this view suggest that if compromises are to be made they should be pragmatic and based on policy rather than principle. This article disputes this thesis and defends compromise as both principled and democratic. The first section distinguishes a shallow compromise based on the maximal satisfaction of exogenously defined preferences from a deep compromise resulting from reasoning on principle, and argues it proves impossible to avoid the latter. The second section suggests that the obligation to compromise forms part of the ethos of democracy, whereby citizens must agree despite their disagreements. The third section concludes by showing that while representatives will almost certainly betray their electoral mandate if obliged to make only shallow compromises, they can legitimately engage in deep compromises for their voters when they reason as they do.