Search query processing includes receiving a search query input string from a user of a mobile device and comparing the search query input to a personalized dictionary of the mobile device, determining a suggested completion for each match in the comparison, and providing the suggested completion to the user for selection. The user can select the suggested modification, if desired, and the completed query can be submitted to a search facility. Personalized dictionaries can be generated from analysis of previously submitted search queries. The analyzed search queries may have been submitted by the user, as well as by other users with similar interests. The analysis of search queries may categorize users into clusters or groups of persons having similar interests.