A system and method for use by website operators and advertisers to place interstitial advertisements on websites. The system uses an Internet dispatcher server and a mass storage device containing one or more databases storing advertisement command files pertaining to placements of advertisements that are stored in an advertisement server. The method comprises the steps of selecting ad files stored in a computer ad server, designating the url for the ad file, the url for the website page where the ad will be displayed, the url for the websites to which a user will be directed depending on the user's reaction to the advertisement, storing in a dispatcher server database a data string representing the ad placement commands with a url representing a dispatcher server-based application to execute said ad placement commands, and including said data string on said website for launching said dispatcher server command file.