We compare two separate but related classification schemes in the area of medical information in order to better understand how they might be used together and inform one another. First we examine a "professional" scheme, the thesaurus of Medical Subject Headings (MeSH) produced by the U.S. National Library of Medicine. We contrast this with the "naïve" scheme used by the consumer health website, WebMD.com. Using the term autism we compared the strengths and limitations from the perspective of vocabulary, syntax and classificatory structure, context, and warrant. We conclude that in terms of vocabulary and concepts, MeSH may benefit from WebMD's approach to ongoing updates and currency as well as the contextualization of terms. At the same time, WebMD may benefit from some form of vocabulary control for richer expansion of terms and archival retrieval.