An analysis of means (ANOM) procedure is suggested for testing the significance of two-factor interactions in fixed-effects balanced designs. When at least one factor is at only two levels, the suggested procedure uses the exact critical points for the ANOM. New critical points are given for the case in which both factors are at more than two but fewer than six levels. The procedure can be extended to higher-order interactions, but the quantities being plotted become so complex that they are of little use in assessing practical significance.