We describe a technique for the control of production rules firing in an object-oriented setting. This technique is based on the separation of control rules from ordinary domain rules. Control rules operate on "control objects" which are created during the reasoning process of the rule base under control. They constitute a separate and independent rule base which contains a declarative specification of the control strategy. Control objects build up an inheritance hierarchy and the associated metabase is constructed via rule base inheritance in a hierarchical manner which parallels the taxonomy of control object classes. AI Topic: Knowledge Engineering Domain area : Explicit control of reasoning Language: Smalltalk-80 Status: Research Application Effort: 1 person-years Impact: This architecture is used for real time monitoring of patients in intensive care units.