Abstract: A multi-provider response selector (MPRS) receives requests and provides respective selected responses. Each request includes respective selection criteria (such as keywords and demographic/geographic information) and/or respective other information (such as page location/time and demographic/geographic information). The MPRS uses the respective selection criteria to fill each of the requests (obtaining the respective selected responses) from one of a plurality of response providers, where the response providers are optionally selected in an order determined by the respective other information and/or other factors such as value returned from the response providers. Optionally, a content server receives content requests for respective specified content, generates requests for the MPRS, and returns the specified contents along with respective selected responses.