ople may be biased to leam categories which not only capture structure in the environment but organize this knowledge in a manner easy to use in reasoning. Concepts organized to contrast consistently on the same attributes as sister categories within a hierarchy may be particularly useful in guiding induction. W e assess whether systems of novel categories organized in this maimer were also easier to leam. Supervised concept learning was dramatically easier in the consistent over inconsistent contrast condition. W e tested whether several models of concept learning would show sensitivity to consistent contrast, as people did, including assessment of a model designed to use information about consistent contrast, TWILIX. None of the models tested (ALCOVE, rational analysis, and TWILIX ) showed muc h sensitivity to the Consistent/Inconsistent contrast. People may flexibly adjust their learning strategy to capitalize on simple regularities when available, in a manner not incorporated in these concept learning models.