I offer the first sustained defence of the claim that ugliness is constituted by the disposition to disgust. I advance three main lines of argument in support of this thesis. First, ugliness and disgustingness tend to lie in the same kinds of things and properties (the argument from ostensions). Second, the thesis is better placed than all existing accounts to accommodate the following facts: ugliness is narrowly and systematically distributed in a heterogenous set of things, ugliness is sometimes enjoyed, and ugliness sits opposed to beauty across a neutral midpoint (the argument from proposed intensions). And third, ugliness and disgustingness function in the same way in both giving rise to representations of contamination (the argument from the law of contagion). In making these arguments, I show why prominent objections to the thesis do not succeed, cast light on some of the artistic functions of ugliness, and, in addition, demonstrate why a dispositional account of disgustingness is correct, and present a novel problem for warrant-based accounts of disgustingness (the ‘too many reasons’ problem).