He held posts in the U.S. Treasury Department, the Smithsonian Institution, and the U.S. Department of the Interior until 2000, and worked as director of the National Fish and Wildlife Foundation and the National Zoological Park until 2009, when he was nominated by President Barack Obama as director of the United States Office of Personnel Management.

[2] Berry served in management for the Montgomery County government from 1982 to 1984 and as staff director of the Maryland Senate Finance Committee from 1984 to 1985.

Berry was appointed Assistant Secretary for Policy, Management and Budget at the U.S. Department of the Interior during the Clinton administration, serving from 1997 to 2001.

[2][7] At the Interior Department, Berry improved credit union and continuing education options, oversaw the expansion of department programs to improve employees' work-life balance, and held town hall meetings with Interior employees and used their suggestions to upgrade a cafeteria and health center.

[9] Berry worked to create a complaint procedure for employees who experience discrimination because of their sexual orientation, to expand relocation benefits and counseling services to domestic partners of employees, to establish a liaison to gay and lesbian workers, and to eliminate discriminatory provisions of the National Park Service's law enforcement standards.

[2][10] Berry was appointed from October 1, 2005, to serve as director of the National Zoo, which had been found to have shortcomings in record keeping and maintenance.

[9] This included a twenty-year capital plan, securing $35 million in funding to provide for fire protection, and beginning renovations to animal houses.

[17] Berry had stated support for benefits for same-sex partners of federal employees and a repeal of the Defense of Marriage Act.

[19] At the time, Berry was, according to the Human Rights Campaign, the highest-ranking openly gay official to serve in the executive branch in any U.S.