This paper describes an antecedent-driven pro-duction system, YAPS (Yet Another Production Sys-tem) which encodes the left hand sides of produc-ion rules into a discrimination net in a manner similar to that used by Forgy ([Forgy 811, [Forgy 791) in OPS5. YAPS, however, gives the user more flexibility in the structure of facts in the data- base, the kinds of tests that can appear on the left hand side of production rules and the actions that can appear on the right hand side of the rules. This flexibility is realized without sac-rificing the efficiency gained by OPS5 through its discrimination net implementation. The paper also discusses how YAPS can be used in conjunction with object oriented programming systems to yield a sys-tem in which rules can talk about objects and objects can have daemons attached to them. It discusses methods of dividing YAPS into independent rule sets sharing global facts.