1. One or more computer storage media having computer-executable instructions embodied thereon that, when executed by a computing system having a processor and memory, cause the computing system to personalize a language model for a particular target user based on user history information, the computer-executable instructions causing the computing system to: receive usage history information for a target user from one or more sources; parse the usage history information to identify entities and user actions associated with the entities; access a generalized knowledge source that is not personalized for the user, wherein the generalized knowledge source comprises indicators of relationships between entities in a domain; map the identified entities and the identified user actions to the generalized knowledge source, thereby creating a personalized knowledge source, the personalized knowledge source comprising indicators of relationships between the identified entities and the identified user actions, and the entities in the domain, the indicators comprising probabilities associated with the relationships, and the mapping comprising at least one of incrementing a count of one or more entities or calculating a weight of one or more entities; utilize the entities, relationships, and probabilities in the personalized knowledge source to build a personal language model for the target user; and utilize the personal language model for computer-performed speech recognition or spoken language understanding for the target user.