Everybody knows that Thomas Watson, Sr. (1874-1956), built IBM into a big computer company and was a business leader. But "everybody" is wrong. Thomas Watson, Sr., did not build the IBM we now know; his son, Tom Watson, Jr., did this after he moved into the company's top management in 1946, only thirty-two years old (though the father stayed on until 1956 as a very active chairman). The father's IBM was never more than medium-size; as late as 1938 it had only $35 million in sales. Of course, it did not make or sell computers; its mainstays were punch-card machines and time clocks.