Rod thresholds were measured at a 5 eccentricity with flashes of 490 nm light entering the periphery of the pupil, while the excitation of rods and cones were independently varied by manipulating the wavelength and troland value of a 102 background. Interactions between rods and cones, revealed by unequal rod thresholds against backgrounds of equal scotopic troland value, depended upon the wavelength and troland value of the background, but not upon the size or duration of the test flash. Such interactions were not observed under the conditions of Flamant and Stiles (1948) unless the background troland value was greater than what they used. Thus, these findings resolve an apparent conflict in the literature. © 1979.