As the Congressional Black Caucus' 15th legislative weekend gets under way here, the 20 black members of the House of Representatives may be feeling a little bit like Davids. They haven't yet felled Goliath, but if they keep twirling their slingshots, one of their stones may just find its way to the giant's skull.

In a decade and a half, the caucus has gone from a group many people scoffed at as powerless to one of prominence. Rep. William H. Gray III (D-Pa.) is chairman of the important House Budget Committee. Rep. Augustus F. Hawkins (D-Calif.) heads the House Education and Labor Committee. Caucus members chair a total of five of the 22 standing committees, two of the five select House committees, and hold high-ranking seats on other influential panels, including Ways and Means.

Indeed, the caucus even demonstrated its ability to create change in the international arena. Members played key leadership roles in bringing about economic sanctions against South Africa.

But now some people are beginning to ask another question about the caucus: Can this relatively new organization of black politicians use some of the same tactics it employed in the South African crisis to address some of black America's pressing domestic concerns?

Although the caucus has chosen an international theme for this week's activities, the question doesn't suggest that anyone is dissatisfied with that focus. Not only is such a theme appropriate for the year's largest national black political gathering, it's also an important step in black America's -- and the caucus' -- coming of age.

For much of the last 15 years, the caucus has been breaking out of one or another of the prisons of other people's expectations. In the early days, caucus members' colleagues expected them to be only civil rights experts. "They did not want to deal with the fact that we could speak with expertise in other areas," Rep. Louis Stokes (D-Ohio) recalled the other day.

When the caucus began to focus on budget priorities and present budget alternatives, other colleagues -- as well as members of the news media -- wondered, open-mouthed, what they knew about economics. (Ask Bill Gray that question today.)

And the international arena was definitely considered off-limits. When Del. Walter E. Fauntroy (D-D.C.) and Joseph Lowery of the Southern Christian Leadership Conference went to Beirut in 1979, many white members of Congress and others severely criticized them for talking to Yasser Arafat and, indeed, meddling in international politics. But this year, Rep. Gray sponsored the original antiapartheid bill, which later prodded President Reagan to impose limited economic sanctions on South Africa. At the same time, Rep. Ronald Dellums (D-Calif.) has become recognized as a leading spokesman on nuclear warfare.

Says Fauntroy: "This year's focus is a recognition that black Americans understand the relationship between our politics abroad and their impact on domestic conditions. The very jobs and occupations by which we had begun to make economic progress are those being exported abroad."

So the question of whether the caucus can begin to help generate a similar turn of events on the domestic scene, as it has on the international scene, is really asked because the group has been effective despite the odds.

In the South Africa situation, however, a key element has been the existence of the independent Free South Africa Movement. This organization, working in conjunction with some caucus members, has been at the center of the conscience-stirring protests, both at home and abroad.

Unfortunately, no group similar to the Free South Africa Movement exists on the domestic front to take the lead. Not only has the country's chief civil rights organization, the NAACP, failed to take an active and effective leadership role in the face of unprecedented attacks on decades of civil rights gains, it has not even broadly communicated a mission. Sadly, like many other civil rights groups, it seems almost moribund.

Ironically, when the civil rights movement was at its zenith, the Black Caucus did not exist. Now that the Black Caucus has come to prominence, the civil rights movement is in a decline. Of course the two are related in that many caucus members participated in the civil rights movement.

What is needed at this time is a revitalization of the civil rights movement -- one, in my opinion, that includes disadvantaged whites and all Americans who suffer injustices. For in the end, Goliath is neither black nor white, but injustice personified. And the stones from the slingshots of the Black Caucus are hurling through the air in the right direction.