Robert L. Maddox, the executive director of Americans United for Separation of Church and State, has resigned effective April 1.
Mr. Maddox, a Southern Baptist minister who had led the organization for the past eight years, will become pastor of a Baptist congregation in Bethesda, Md.
During Mr. Maddox's tenure, the watchdog group disseminated information on church-state issues and filed lawsuits over the use of public funds in religiously affiliated schools.
Previously, the 54-year-old Mr. Maddox served as a speechwriter and liaison with religious organizations in the Carter Administration and as a pastor in Texas and Georgia.
The search for a successor has begun.
The San Francisco Board of Education last week named Waldemar Rojas, the head of special-education programs in the New York City school system, as its next superintendent.
Mr. Rojas, 46, will succeed Superintendent Ramon Cortines, who is retiring in June. The board selected the Brooklyn native after a five-hour meeting on March 10 that was supposed to narrow the field of candidates from four to two.
A school-district official said board members found they had a consensus on Mr. Rojas, so they voted to offer him a contract. The other finalists were Rudy Crew, the superintendent of the Sacramento, Calif., schools; Robert Ferrera, the superintendent in Minneapolis; and Joan Raymond, the superintendent in River Forest, Ill.
Some community activists were upset over the board's failure to select Mr. Crew, who is black. Mr. Rojas is of Puerto Rican descent.
As head of special-education programs in New York City, Mr. Rojas oversees a program with twice the budget and enrollment of the entire San Francisco system, which enrolls 63,500 pupils. Mr. Rojas will earn about $120,000 a year.