A distinction is drawn between two classes of denominal verbs, and four experiments examine the effects of this distinction on the production and comprehension of denominalizations. Rule-derived (RD) denominals are formed from nouns belonging to semantic categories whose members share the same meaning when they are used as verbs. For instance, denominal verbs formed from vehicles generally mean "to travel/convey by x," where x represents the specific vehicle. In contrast, idiosyncratically derived (ID) denominals are drawn from categories whose members possess diverse meanings when they are used as verbs. Thus, to fish means "to try to catch fish," whereas to dog means "to chase tirelessly." Because the verb meanings of rule-derived terms are relatively predictable, they might be more easily produced and understood. Experiments 1 and 2 show that speakers are more likely to select RD terms for denominalization and are faster at creating denominal uses for RD terms. Experiments 3 and 4 show that RD denominals are rated as easier to understand than ID denominals, and that they are interpreted more uniformly across readers. The Discussion considers pragmatic accounts of the results, the theoretical basis for the distinction between RD and ID terms, and the more general point that experimental methods can be used to study creative uses of language.