A system, method and computer program product is provided that automatically selects certain user segments for and excludes certain user segments from receiving online advertisements (“ads”) via various publisher Web sites included within an online ad network. By automatically determining which user segments should be targeted for the delivery of online ads on each publisher Web site, an embodiment of the present invention can advantageously increase the performance of the online ad network while reducing the amount of cost, time and potential errors involved in managing the network.