Dennis Irwin was born on November 28, 1951 in Birmingham, Alabama but grew up in Atlanta and Knoxville. Early in life he discovered music"inspired by older brothers who coached him in jazz early on"and began playing clarinet. As a teenager, his family moved to Houston, where he played in R&B bands playing alto sax and handling lead vocals. He attended North Texas State University studying classical music focusing on his clarinet. Two friends in the program, drummer John Riley and bassist Marc Johnson turned him on to the upright bass at the age of 19: he thus found his true calling and joined the school’s acclaimed Two O’Clock Big Band.
In nearby Dallas, he worked as a sub with pianist Red Garland, who suggested Irwin move to New York