Hi Ken -- One thing I'd already tried was to have a rule that invokes a sub, and the sub calles the procedure that does the actual processing. Neither F5 for breakpoint nor Stop statements worked there. FWIW, I started with the processing logic in the sub invoked by the rule, same results. Interestingly, if I invoke the sub that does the actual processing from the Immediate Window, breakpoints work like they should. One thing I didn't mention is that I had been kicking off my rule from the "run rules now" part of the Rules and Alerts dialog. Wonder if that's making a difference, because there a dialog open. Any thoughts in light of that? Thanks, Mark