Do you mean, the users are able to really define what they like to see in the report, or, do you mean, the users have pre-defined options to choose how to filter the data?? For the first case, many developers has been asked the same thing, and the answer is no, the user, unless they know how to use the report generation tool such as Crystal Report or SQL Reporting Service, and know the system, they can't "freely" generate any report that they like. For second case, you can pass value by parameters and have the report filter by these parameters, or in Crystal Report case, you can add the selection criteria to SelectionFormula that is formed by the user interface.