Founded in 1887 and celebrating its 125th anniversary in 2012, the Boston Athletic Association is one of the oldest sports organizations in America. It's best known today for its signature annual event, the Boston Marathon, which is the third-largest marathon and attracts tens of thousands of participants and worldwide media coverage. But the B.A.A. has also been amazingly prescient in anticipating what would become one of the major social trends of the late twentieth and early twenty-first century: the modern fitness movement. Consider some of the B.A.A.'s firsts: Nine out of the fourteen members of the US team participating in the modern Olympic Games in Athens (1896) were B.A.A. athletes. The B.A.A. launched the first US marathon, the Boston Marathon, in 1897. The B.A.A. pioneered and actively promoted many of today's popular sports, including football and water polo. The original B.A.A. club house, in the historic Back Bay section of Boston, is the precursor of today's health club. Still, the B.A.A. story is not simply one of athletic achievements and firsts. It's also the dramatic story of people and the times in which they lived-a social history that unfolds in nineteenth-century Boston but takes readers around the world, up to the present, and includes a large and international cast of characters. A wonderfully illustrated history, B.A.A. at 125 highlights the Boston Athletic Association's important role in American sports history.