Bratton, who has been praised for helping reduce crime and easing tension between the public and police, says collaborative work among government agencies has become especially important after September 11th.
Terms of the book deal have not been released. The book is tentatively titled, "Collaborate or Perish!"
The book is set for release in 2011 by Broadway Business, a brand name of Random House, Inc.
Bratton, 61, will leave the department in October and will work for Altegrity Security Consulting Inc., a global security firm based in Virginia.
Bratton is the author of a 1998 memoir, "Turnaround," which he wrote for Random House while he was New York City's police commissioner.
Bratton says his co-author Zachary Tumin is a longtime associate who proposed the new book idea.
Bratton says he will contribute stories, concepts and ideas, while Tumin will write much of the book.
Bratton says he would have worked on the new book even if he had remained with the LAPD.
He's said money and a chance to work with a friend, Michael Cherkasky, who heads the company hiring him are among the reasons he's leaving the LAPD.
Tumin is associate director for programs in technology at Harvard University's John F. Kennedy School of Government. He's the former executive director of New York City's Division of School Safety.
In 1994, Tumin was reprimanded and docked three days vacation for failing to seek competitive bids for contracts that went to two consulting companies, one of which employed Bratton, and with whom Tumin had ties.