A method and apparatus for associating methods or attributes on a per-instance basis is provided. One technique for providing "per-instance attributes" involves properties and property bundles. A second technique for providing "per-instance attributes" involves categories wherein the instance can be thought of as being "placed" into one or more categories. A technique for providing "per-instance methods" involves policies. In any of these techniques, providing per-instance properties may be used in any of the following ways: (1) different instances of the same class are associated with different properties where the properties are not in the class; and (2) two instances of two different classes are associated with the same property where the property is not in either of the two classes.