The stimulus properties of the letters b, d, p, and q were investigated in an attempt to demonstrate that the common reversal of these letters by beginning readers is in part determined by the vertical aspect of the stimulus figure. One hundred eighty kindergarteners were randomly selected from a racially mixed population and randomly assigned to one of four visual matching of letters tasks. All tasks presented letters of uniform size, shape, density, and presentation except for certain variations relevant to each of the four experimental treatments. All four treatments required subjects to match lower case letters to one lower case stimulus letter printed in the center of the page two inches from the top. Subjects were instructed to draw a cross on each letter on the rest of the page that was exactly the same as the stimulus letter at the top. The letters presented on the rest of the page were designated response letters. The response letters included those identical to the stimulus letter and three foils. The results indicated that the vertical properties of b, d, p, and q influence the letter reversal behavior of kindergarteners. In addition, reducing the dominance of the vertical aspects of these letters resulted in marked reduction of reversal errors. (WR)