Kenya has been recognized globally as maize success story since the 1970s. Released on the eve of independence, Kenya’s first maize hybrid diffused faster than did hybrids in the U.S Corn Belt during the 1930s-1940s. In recent decades, policy researchers have lamented that earlier gains in maize productivity have not lived up to their potential. Claims of stagnating yields and stagnating adoption are offset here, at least in part, by longitudinal survey data showing rising yields and adoption rates on farms. Tegemeo survey data confirm that Kenya has reached its adoption ceiling years ago in the major maize producing zones of the country, and is near to doing so in other zones. Data show adoption rates topping 80% of farmers.