12. A computer system comprising: at least one processor; and memory comprising instructions stored thereon that when executed by at least one processor cause at least one processor to perform acts comprising: receiving a query; inferring a query reading level representation from one or more user input actions associated with the query, the query reading level representation comprising a reading level distribution over multiple distribution reading levels, with the reading level distribution over multiple distribution reading levels comprising, for each of the multiple distribution reading levels, an indication of a probability that an item at that distribution reading level will be understood; in response to the query, ranking search result items, the ranking being based at least in part on the query reading level representation for the query and reading difficulty level representations for the search result items; and in response to the query, returning the search result items and one or more indications of the ranking.
17. The computer system of claim 12 , wherein inferring the query reading level representation comprises analyzing one or more user-selected documents.