In 1993, he was named Assistant Secretary for Planning and Evaluation at the United States Department of Health and Human Services (HHS), where he served as co-chair of Bill Clinton's Working Group on Welfare Reform, Family Support and Independence.
At HHS, Ellwood played a key role in the administration's development and implementation of critical social policy.
He is also a faculty affiliate of the Joint Center for Poverty Research at Northwestern University/University of Chicago and serves on the board of Abt Associates and the Malcolm Hewitt Wiener Foundation.
[citation needed] In 2016, Ellwood became chair of the US Partnership on Mobility from Poverty, an effort funded by the Bill and Melinda Gates Foundation and run by the Urban Institute.
The group of 24 scholars and activists is a "collaborative aimed at discovering permanent ladders of mobility for the poor.