A globally-recognized maize “success story” since the 1970s, Kenya’s first maize hybrid diffused faster than did hybrids in the U.S Corn Belt during the 1930s-1940s. Today, a hybrid released in 1986 still dominates on farms in Kenya, despite the dramatic increase in the number of hybrids, breadth of seed suppliers, and range of hybrids sold as seed markets liberalize. 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. However, as the overall percent of maize farmers growing hybrids tops 80 percent and the seed industry matures, the slow pace of hybrid replacement may still be cause for concern. This paper begins an exploration of factors affecting the age of hybrids on farms in Kenya. We find a strong farmer response to the seed-to-grain price ratio—evidence of a commercial orientation even on household farms, and also of the need to “get (seed) prices right” in the industry.