Women and minorities are underrepresented in the top levels of most legislative branch agencies and may not get a boost in the near future, according to a new report.

The study, which will be released at a hearing today, was completed as part of an investigation by the House Oversight and Government Reform Subcommittee on Federal Workforce, Postal Service and the District of Columbia.

Its conclusion: Agencies should improve the diversity of their top ranks by looking outside the agency and by hiring women and minorities for positions that feed into senior jobs.

The report comes several months after the subcommittee held a hearing on similar issues within the executive branch, based on a May 2007 Government Accountability Office report. The subcommittee now has similar questions about the upper levels of the legislative branch, Subcommittee Chairman Danny Davis (D-Ill.) said.

“One of our goals is to have the most well-trained, most productive but also the most diverse work force that can be generated,” he said. “We’ve been concerned about SES [senior executive service] rank, and how will women and minorities reach those opportunities.”

The SES rank typically includes those positions that are in the top tier of the agency — positions like “deputy director” and “unit chief.” Most legislative branch agencies don’t use the SES rank, but they have positions that are equivalent. They pay about $150,000 a year and include senior officials who are not political appointees. The numbers of such positions in each agency vary considerably, from the 140 in the GAO to 15 in the Architect of the Capitol’s office.

Overall, minorities make up 16.8 percent of those positions in the agencies and women make up 35.8 percent — less than the makeup of the collective work force at the agencies. And those numbers aren’t on the upswing: Since fiscal 2002, the numbers for minorities have stagnated and female representation has only risen slightly. Another problem identified by the report is the lack of diversity in the “successor pools,” or the positions that feed into senior spots. In several of the agencies, these have even less diversity than the senior positions, leaving precious little to draw from.

And while Davis asserted that representation of female and minority employees at the senior level in the legislative branch compares favorably against findings within the executive branch, he also acknowledged that there are significant disparities between different Congressional agencies.

“Some legislative branch agencies are doing much better than others,” he said.

The Hill agencies won’t see the report until today’s hearing, but they supplied the subcommittee with all the information used in the report — and some officials talked about how those numbers reflect on their organizations.

The Congressional Budget Office fared worst, with only 7.9 percent of its top positions filled with minorities. Women did a little better, making up 18.4 percent of that rank. But it all paled in comparison to the CBO’s work force as a whole, which is made up of about 16 percent minorities and about 43 percent women — a possible sign that minorities and women aren’t making it up the ladder.

The problem is an applicant pool devoid of diversity, CBO Director Peter Orszag said. Forty percent of CBO positions require an economics Ph.D., and yet minorities who are U.S. citizens make up only 4 percent of those getting degrees, he said.

“I think the economic field in general suffers from a lack of diversity in the flow of students choosing to study economics,” he said, “and I think the field would be brighter, richer and better if it was more diverse.”

Orszag said his agency has to deal with several factors. Not only is the pool of minority applicants small, the lower pay of government jobs makes attracting sought-after minorities difficult, he said. To close the gap, Orszag said the CBO seeks out minority applicants and works with organizations to encourage students to study economics. But it’s like “the tail wagging the dog,” he said, especially when his agency’s work force numbers only 227 employees.

“The outside opportunities for economists have become increasingly attractive,” he said, citing hedge funds and think tanks. “Basically, I have to make this place as exciting and interesting and vibrant as possible because we simply can not pay.”

On the other end of the spectrum is the Library of Congress, which had the largest proportion of minorities and women of all the agencies covered. About 20 percent of its top positions are filled with minorities, while about 44 percent are made up of women.

That record is a result of hiring practices and programs that emphasize bringing in underrepresented groups, said Dennis Hanratty, LOC’s director of human resources services. Each open position yields a new staffing plan that maps out how to enrich the applicant pool, while hiring programs recruit from black and Hispanic organizations.

The Library hits some roadblocks because of limited resources — especially under the current continuing resolution — but Hanratty said the agency is proud of what it has done.

“We certainly want to be as diverse as possible, but I think for us, the critical measurement is how we’re doing against the rest of government, and I think our track record is good,” he said.

The other agencies examined in the report — the Government Printing Office, the Capitol Police, the AOC and the GAO — all ranked somewhere in between the CBO and LOC in their proportions of women and minorities in top jobs.