Guy Morse, 61, will retire from the Boston Athletic Association at the end of the year, concluding a 28-year career with the organization. He has served as race director for the Boston Marathon, executive director, and, most recently, as senior director of external affairs.

Under Morse’s leadership, the Boston Marathon instituted prize money and secured long-term corporate sponsorships, ensuring its status as one of the preeminent marathons in the world. With Morse providing direction, the event grew from an amateur race with approximately 5,000 participants to one with 27,000 runners, including the top male and female marathoners in the world. And the top marathoners now compete for more than $800,000 in prize money.