Kellerman was born in New York City but his family moved to Los Angeles in 1959, and Kellerman attended UCLA, from which he received a B.A. in psychology. He claims to have "worked his way through college as a cartoonist, illustrator, journalist and editor, as well as by teaching guitar."
However he side-stepped the writing world until 1985. He enrolled in in a PhD program in clinical psychology at the University of Southern California, receiving his PhD in 1974 for a dissertation on attribution of blame for childhood psychopathology. He is currently a Clinical Professor of Pediatrics at USC but he does not practice.
Kellerman told Los Angeles Times that he rediscovered writing when he "picked up a Ross Macdonald novel, The Underground Man, which cost him a dime. Reading it later, something clicked. "I said, 'This guy is a psychologist!' " Kellerman picked up the influence of Freud on these private-eye novels. "I thought, 'I'm a psychologist: Maybe if I'm good enough, I can bring something special.'" Macdonald's Lew Archer novels — and Joseph Wambaugh's police procedurals — offered an orientation for Kellerman. (LAT, Scott Timberg, 3/29/11)
Kellerman's series hero is Alex Delaware, like himself a child psychologist. Beginning with When the Bough Breaks (1985), he has explored the world of crime from a child's point of view, writing of such topics as repressed and recovered memories, childhood loss, and juvenile predatation.
He has written two books with his wife, novelist Faye Kellerman, whom he married in the early 80s.
''We don't discuss the formulation of ideas, but we read each other and critique,'' Faye Kellerman told the New York Times. ''He's his own toughest editor, and I'm my own. I take his advice a lot. I cogitate over it, but he has a sharp eye and ear. He's my best friend, my best booster.'' (Martin Arnold, NYT 10/24/02)