IT has become a standard conservative talking point: Black activists focus on police brutality but ignore violent crime in black neighborhoods. Last month Rudy Giuliani said on Fox News: “If they meant ‘Black Lives Matter,’ they would be doing something about the way in which the vast majority of blacks are killed in America, which is by other blacks.”

Claims like Mr. Giuliani’s aren’t just offensive or misplaced — they’re demonstrably wrong. While Black Lives Matter receives deserved attention, countless grass-roots organizations — many of which were founded by bereaved black women — are doing remarkable work to prevent and reduce crime. They protest violence, testify at city council hearings, press for gun-control reform and collaborate with politicians, faith-based organizations and, yes, even the police.

I spent 20 years studying anti-crime politics — observing community meetings, interviewing lawmakers and activists and analyzing city council hearings about crime. I found groups organizing on everything from “barking dogs to shootouts,” as one legislative aide told me. Their activism was impossible to miss.

But this local organizing goes largely unnoticed by politicians, scholars and the news media, all of which focus instead on large national groups with big budgets and expensive lobbyists.