The perception of semantic similarity derives from distinct processes of comparison and integration. A dual process model of conceptual combination claims that attributive combination (e.g., umbrella tree) entails comparison, while relational combination (e.g., pancake spatula) requires integration. The present research uses similarity as a test of this dual process model. Participants (N = 168) were presented attributive and relational conceptual combinations. Half of the participants interpreted the combinations before rating the similarity of their constituent concepts, while the other half provided (...) similarity ratings without interpreting the concepts together. The experiment revealed that attributive combination decreased the perceived similarity of the constituent concepts, whereas relational combination increased the similarity of the constituents. This result indicates that attributive and relational combination occur via distinct processes. Results of a post‐test (N = 60) suggested that these effects were specific to the particular concepts compared or integrated, and do not generalize to other concepts not compared or integrated. The present research thus supported a dual process model of conceptual combination by demonstrating differential effects of comparison and integration on the perception of semantic similarity. (shrink)