Stroop stimuli in which the two competing aspects are equally compatible with a naming response are described. They consist of large uppercase letters constructed from an array of small printed uppercase letters or neutral symbols (e.g., asterisks). The elements in the array can be congruent, incongruent, or neutral with respect to the letter defined by the array. In a letter naming task, naming latencies were significantly longer for incongruent stimuli than for congruent or neutral stimuli. Interference was increased for stimuli in which the competing aspects were visually confusable, but not for stimuli in which the competing aspects were acoustically confusable. The results are discussed in relation to some theories of Stroop interference.