Creative thinking has long been associated with spreading of activation through concepts within semantic networks. Here we examine one potential influence on spreading activation known as the fan effect: increasing concept knowledge leads to increasing interference from related concepts. We tested whether cue association size-an index of semantic richness reflecting the average number of elements associated with a concept-impacts the quantity and quality of responses generated during the alternate uses task (AUT). We hypothesized that low-association AUT cues should benefit quality at the cost of quantity because such cues are embedded within a semantic network with fewer conceptual elements, thus yielding lesser interference from closely-related concepts. This hypothesis was confirmed in Study 1. Study 2 replicated the effect and found an interaction with fluid intelligence, indicating that cognitive control can overcome constraints of semantic knowledge. The findings thus highlight costs and benefits of semantic knowledge for creative cognition.