A once-homeless mother of twin girls appreciates the work of the nonprofit that put her family back on its feet.

Tomorrow, she and the twins will join about 25,000 other people at Freedom Plaza to begin the 12th annual Help the Homeless Walkathon, which benefits 174 local groups that provide services to the homeless. For many of the groups, money raised by the 5K walk provides one-third or more of their annual budgets.

Vonda Walker and her 8-year-old girls will designate their pledges and registration fees for Crossways Community in Kensington. Walker arrived at Crossways Community just out of the military, with her small children, no job, no skills applicable to the civilian world and no place to go.

For two years, Walker and her children lived in the Crossways Community apartment building. She studied culinary arts and took courses in life skills such as budgeting. On graduation from the program, she got a part-time job as a cook in Montgomery County schools and filled in with other part-time work. Recently, the school system hired her full-time. She moved into a new apartment and is saving for a better car.

Now, it's payback time.

Each participating nonprofit recruited walkers to raise pledges and pay entrance fees on its behalf--funds expected to total about $2 million. Additionally, 250 corporate sponsors are donating $2 million. Some sponsors have designated a particular nonprofit agency to receive their gift. The remaining money will be distributed by a committee put together by the Fannie Mae Foundation, which is sponsoring the walk and paying all administrative costs. All money raised goes directly to service providers.

The walk started when 150 Fannie Mae employees walked in Rock Creek Park and raised $90,000 for four homeless providers.

This year, the nonprofits that will benefit from the walk include groups that help families and individual adults with addiction problems or mental illness. Bright Beginnings has early childhood education for homeless children. Unity Health Care and the Arlington Free Clinic provide medical care. Other groups offer legal help, dental work, training, shelter, food, or clothing for job interviews.

Those wanting to join the walk can sign up on the Web, at www.helpthehomelessdc.org, or at Freedom Plaza at 8 a.m. tomorrow.

CAPTION: 5K Walkathon for the Homeless