Wade Horn, the Bush administration's point man for welfare reform, Head Start and abstinence education, resigned Monday as assistant secretary for children and families.

In the Department of Health and Human Services, Horn oversaw a $46 billion budget and 65 programs that serve vulnerable children and families. He is best known for his work on issues embraced by social conservatives, such as more money for faith-based groups and organizations that work to help couples improve their marriage.

Republicans gave some of those programs significant funding increases when they were in the majority. For example, Congress set aside for the next five years up to $100 million a year to promote marriage and $50 million a year to produce committed fathers. Similar expansions may be harder to come by with a Democratic majority.

The Senate confirmed Horn in July 2001. He is a child psychologist who served as president of the National Fatherhood Initiative before his nomination by President Bush. The initiative's mission is to increase the proportion of children growing up with responsible fathers.

Horn told his staff Monday that he would be accepting a position in the private sector. His resignation is effective Sunday.

Robert Rector, a senior fellow at the Heritage Foundation, a conservative think tank, said Horn tackled the most important social issue in the United States while others ignored it — the decline of the institution of marriage.

About 4 in 10 children are born outside of marriage, and those families participate in means-tested assistance programs at much higher rates than do married families, Rector said.

"The government went decade after decade pretending the problem didn't exist," Rector said. "He raised the public profile. He directly addressed it over and over again. He's the first one to do that. Others in this position were frightened away by the issue."

Others viewed Horn's work more skeptically. Horn oversaw a dramatic increase in funding for abstinence education, which now exceeds $200 million a year. Some groups say it's important to promote abstinence to youth, but that message won't work for all. They would prefer that the administration fund comprehensive sex education programs, which would include abstinence as part of the curriculum.

"Because (the abstinence funding) is so contrary to public health, our hope is the next assistant secretary there can have a firmer footing on what the evidence says," said William Smith, vice president for public policy for the Sexuality Information and Education Council of the United States.