This paper discusses how Information Systems can support marketing decision making in the promotional area. We deal mainly with the use of Consumer Panel data, although reference is also made to the integration of other data sources - sales and store audit - alongside panels through a fuller Information Systems approach. We commence by reviewing the various types of promotions, and promotional objectives. Next, we review briefly the value of consumer panel data in this context, and go on to discuss why Information Systems are invaluable when coping with this data. We describe an actual Information System of this type, and show two case histories which illustrate how promotional problems were solved through the use of this system.