After publishing his first book, The Felon, in 1970, Irwin joined the Sociology faculty at San Francisco State University, where he taught for 27 years. Over the course of his lifetime, Irwin was a passionate advocate for prison reform, inspired by his experience at Soledad, as  well as by various studies he conducted into the lives of inmates. In 1967 Irwin founded Project Rebound, a program on the San Francisco State University campus that helps those coming out of prison go to college. In the coming decades he co-founded Prisoners  Union, an organization that helped prisoners fight for their civil rights, as well as the Convict Criminology movement, an idea he helped bring to light at a 1997 panel presentation at the American Society of Criminology’s annual conference. The movement brought to light the growing number of former inmates who had gone on to earn PhDs and continue to critically examine the criminal justice system. In addition, Irwin had been on the board of directors of The Sentencing Project since 2005, a national prison reform advocacy organization.

Irwin was inspired to write Lifers after he completed a study of California State Prison at Solano and became interested in the inmates who were serving life sentences. The number of these inmates has rapidly accumulated in recent years in California, and Irwin noticed that most of these "lifers" had become highly motivated to change themselves and engage in many rehabilitative (e.g. education and vocational training) and “self-help” programs. Although these inmates have shown remorse and desire to give back to society through public service work upon release, parole is not a simple matter. The parole board, the governor, and the California Supreme Court have been guided by a “tough-on-crime” philosophy that sidesteps the state’s sentencing laws. Most oftentimes lifers are denied parole year after year, even though they have served two to three times the number of years the sentencing law dictates.

John Irwin is survived by his wife and four children, one of whom is also a Routledge author. Katherine Irwin, a professor of Sociology at the University of Hawaii, Manoa is co-author of the best-selling Beyond Bad Girls: Gender Violence and Hype, published in 2007.