Cousy played at Holy Cross during his college career. In the NBA, he led his team to six championships, including the 1957 one and five consecutive titles, from 1959 to 1963, after which he retired. The five consecutive titles towards the end of his career were part of a Celtics' streak of eight consecutive championships.
Cousy is the Celtics' all time assist leader with 6,955 assists. He also scored 16,960 points, and participated in the all-star game thirteen consecutive times, picking up the most valuable player award at that game in 1954 and 1957. From 1969 to 1974, he came back to the NBA, as a coach.
Cousy has enjoyed a very public life in retirement. He made a talking cameo appearance in 1994's movie Blue Chips, and has worked at different capacities for the Celtics since his playing days were over. In 1999, he was chosen as one of the NBA's 50 greatest players of all time, and ESPN chose him at number 94 of the 20th Century sports century 100 greatest athletes.