Charles Moskos, 74, a sociologist and expert on the attitudes of armed-services personnel who helped formulate the "don't ask, don't tell" policy toward gays in the military, has died.

The retired Northwestern University professor died May 31 at his home in Santa Monica, Calif., his family said.

His surveys on military-personnel issues, such as morale and recruitment trends, made him widely quoted in the news media. He was best known for the advice to the Joint Chiefs of Staff that led to "don't ask, don't tell."

Under the policy, passed by Congress in 1993 in the early months of the Clinton administration, gays are allowed to serve in the military but are prohibited from engaging in homosexual activity or talking about their sexual orientation.

- AP