When Betty Green retired from her government job in 1977, she decided to spend more time with her three children and bought a piano keyboard so they would stay home and learn how to play. Then she bought a drum set. Then a guitar. And finally an electric bass.

"They were just jamming around in the basement one day and I came up with the idea for a band," said Green, 43. "But if I was going to organize a band, I figured I better learn to play something."

Now, seven years later, Green plays an electric bass and leads her own band. It's called Mother's Band and Show, and it has united her family and is used to reach out to others.

Her daughter Robin sings, and daughter Vonnye plays trumpet. Vonnye Green, a student at Elizabeth Seton Catholic High School, has performed twice for President Reagan at the White House and has recorded two albums at the Kennedy Center Opera House.

Her son, Spencer Green, plays guitar, and her husband Ralph sometimes plays percussions but usually records their performances with a video camera. Professional musicians join in for special engagements. "We wanted to try to send a message with our music that no matter how hard things get we must stick together as a family," said Robin Green. "We believe that a family that prays and plays together, stays together."

Within a year after the band was formed, neighbors began requesting that it play for New Year's Eve parties. As word spread about the quality of its performances, local civic leaders began asking it to play, and Betty Green began giving benefit concerts in prisons and reformatories here.

The band has received more than 100 awards and citations, including commendations from District Mayor Marion Barry. Green pays most of the band's expenses. Green estimates that about $30,000 for equipment and salaries has come out of the family budget since 1977.

"It's a sacrifice," Green said. "But it's worth it. My husband just gave me $250 to do my Christmas shopping, but I'm using that to pay the professionals in the band."

Those professionals include Willie Jollie, who sings with such recording artists as Jean Carne and Phyllis Hyman, and Greg Boyer, a trombone player for the group Funkadelics.

"Mother is one of the nicest people I've ever worked with," said Jollie. "She really cares about using music in a way that helps people."

Last week, Mother's Band and Show performed at the Lorton Reformatory, and this time Green decided to do something different. She asked about 20 young women who live on her block of R Street Southeast to put on a fashion show for the inmates. Although some declined, most went along.

The Band and Show was greeted enthusiastically at the troubled penal institution. When the band's rendition of Chuck Brown and the Soul Searchers' "I Feel Like Busting Loose" began, inmates began to sing and clap.

For Green, it was just another community service, part of what she says is her mission to bring entertainment to "people locked out of the mainstream."

"Somehow God gives me strength to do these things," she said.

Meanwhile, she's content to continue singing and strumming her electric bass, starting each performance with a song written by her daughters, "Have No Fear, Mother Is Here."