(FORTUNE Small Business) – As a child, Aida Alvarez learned a few lessons about running a small business while helping out behind the counter of her mother's restaurant in Brooklyn. For the last four years, she's put those lessons to good use as the head of the Small Business Administration in Washington, D.C. Of course, her Harvard education and the skills she acquired as an investment banker at Bear Stearns and First Boston helped too.

During her tenure, she earned a reputation as a champion of entrepreneurs. With good reason. She doubled the SBA's venture capital investments, launched special programs for rural and inner-city businesses, and broadened the agency's horizons, even guaranteeing loans to independent filmmakers. This year, the SBA will back $20 billion in loans, $6 billion more than when she first walked through the door in 1997. That kind of expansion wasn't easy in the partisan climate of the late Clinton era. Republican members of the Senate small business panel kept a close eye on Alvarez, a Clinton appointee, questioning everything from her travel expenses to the amount she once paid a makeup artist she used for a series of six SBA public information television programs.

Just days before she returned to private life, Alvarez, 51, talked with FORTUNE's Jeffrey H. Birnbaum to discuss her accomplishments and what remains to be done at the capital's most important agency for small business owners.

Was the job what you expected it to be when you first arrived?

I knew there was a mission to help small businesses start, grow, and be successful. I had not focused on the incredible role the SBA plays in giving small business access to the $200 billion federal procurement market. We make sure that 23% of all federal contracts go to small businesses. That's big!

What do you feel was your greatest accomplishment?

We probably got more dollars to small businesses through our guarantees than ever in the history of the agency. In loan activity alone, prior to [the Clinton] Administration, we did $78 billion. In just the last eight years, we did $82 billion. That is a very significant accomplishment for small business.

What was your biggest regret?

Not enough time to do some of the other things. We were just getting an international initiative off the ground.

Your vision of the SBA's reach seemed broader than your predecessors'. You expanded into new areas, including the arts, guaranteeing loans for independent filmmakers. Why?

That's really exciting territory. This is a country in which intellectual property is the collateral that many of the innovators bring to the table, and yet bankers shy away from providing loans to businesses that don't have traditional collateral. We're trying to push the envelope and find a responsible way to gauge the value of intellectual property so that small business [including independent filmmakers] can access the lending market. I hope this gets some traction and that it's not limited to the arts community.

Will the expansion of SBA programs continue, especially in rural and inner-city communities, given the slowing economy?

Absolutely. First of all, it's a very inexpensive investment. There's also a lot of untapped productivity. If we want to continue the economic expansion, we've got to go to parts of the country where there is potential productivity that hasn't been explored. And right now people are getting gun-shy about making equity investments in high tech-type companies.

Where does the SBA most need to offer assistance?

There are gaps in three significant areas. One is lending and financing for international transactions by small business. The next is lending to companies and entrepreneurs whose collateral is intellectual property. The third is lending to entrepreneurs in rural or inner-city communities that have been underserved.

Will the SBA soon have to shrink programs that it expanded in the past, given the credit crunch and the weakening economy?

The conventional wisdom is that when the economy is doing well, SBA activity declines, and vice versa. But you see the opposite, partly because we've restructured the agency. The SBA's overhead has shrunk. We've reduced our staffing by about 27%, yet our output has significantly increased. I don't see any clamor for further reductions.

Now that you're leaving the SBA, what will you do next? Something good, I hope.