A location may be determined by accepting location information from at least two sources using at least two location technologies, for each set of location information from each source, adjusting the location information using at least one of (A) confidence in the source, (B) error range of the source, (C) an error model for the source, and (D) application-specific context information, and combining adjusted locations to generate a final location these location technologies assume a degree of cooperation. The location technologies may include a combination of a "tag" that is placed on the object to be tracked, and one or more receivers/transmitters that work in concert with the tag to locate the object.