Irsay was born in Lincolnwood, Illinois, the son of Harriet (née Pogorzelski) and Chicago businessman Robert Irsay. His father was from a Hungarian Jewish family and his mother was the daughter of Polish Catholic immigrants. Irsay was raised Catholic, and did not know about his father's Jewish heritage until he was fourteen. Jim's brother, Thomas, was born with a mental disability and died in 1999, and his sister, Roberta, died in a car accident in 1971. Irsay attended high school at Loyola Academy in Wilmette, Illinois a suburb just north of Chicago, Illinois and at Mercersburg Academy '78, Mercersburg, Pennsylvania. After high school, he attended, and graduated from, Southern Methodist University in 1982 with a degree in broadcast journalism. Irsay played linebacker for the SMU Mustangs football team as a walk-on, but an ankle injury ended his playing career.