The optimum design of decoupling capacitors on a printed circuit (PC) board has been the subject of debate and opinion for many years. Cause and effect have been difficult to separate from all the other effects occuring on a normal active PC board. Tins work used a specially designed PC board to allow the measruement and characterization of the effects of various decoupling capacitor strageties. Many common opinions and myths are investigated, and the optimum design stragety recommended based upon the measured data in this report.