The NAACP has passed a resolution endorsing same-sex marriage as a civil right and opposing any efforts "to codify discrimination or hatred into the law."
The Baltimore-based National Association for the Advancement of Colored People announced Saturday that its board voted at a leadership retreat in Miami to back a resolution supporting marriage equality.
It said the position is consistent with the equal protection provision of the U.S. Constitution.
Same-sex marriage is legal in six states and the District of Columbia, but 31 states have passed amendments to ban it.
NAACP President Benjamin Todd Jealous, a strong backer of gay rights, says "civil marriage is a civil right and a matter of civil law."
Gay marriage has divided the black community, with many religious leaders opposing it.