You're doing nothing wrong.  At least, as long as you want it to print twice.  :)  Two activations are put on the agenda because both patterns (X+Y and X+Z) are in working memory. Probably your best bet is to split it into two rules in an activation-group. rule "Cannot select X if both Y and Z are not selected" activation-group foo when       Item(code == "X")          not Item(code == "Y") then     System.out.println("Error: You cannot select X unless both Y and Z are selected"); end rule "Cannot select X if both Y and Z are not selected" activation-group foo when       Item(code == "X")          not Item(code == "Z") then     System.out.println("Error: You cannot select X unless both Y and Z are selected"); end Activation of one rule will prevent activation of the other one, resulting in only one error message. --- On Mon, 12/1/08, Vithal Kuchibhotla <vithalklrk(a)rediffmail.com&gt; wrote: From: Vithal Kuchibhotla <vithalklrk(a)rediffmail.com&gt; Subject: [rules-users] Action firing twice To: rules-users(a)lists.jboss.org Date: Monday, December 1, 2008, 11:20 PM Hello All, I have a list of Items that I am inserting into working memory. Here is the rule that is failing: rule "Cannot select X if both Y and Z are not selected" when     Item(code == "X")     (or (not Item(code == "Y"))         (not Item(code == "Z"))) then     System.out.println("Error: You cannot select X unless both Y and Z are selected"); end This rule works correctly when X and Y are there, and when X and Z are there. However, when both Y and Z are missing, the error prints twice. Can anyone tell me what I am doing wrong. Thanks a lot Vithal _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users