Boy Scout leaders from around the country, engulfed in a culture war over homosexuality, gathered for a vote here Thursday on a landmark proposal that would permit openly gay youths — but not openly gay adult leaders — to participate in scouting.

In a secret ballot, more than 1,400 volunteer leaders from scouting’s 270 councils will accept or reject a proposal that has led to strident divisions and debate. …

After publicly wavering, which only fueled the divisions, Boy Scout executives conducted exhaustive research this spring on member attitudes. They devised a plan that they hoped might defuse the debate, opening the door to gay youths but keeping it shut for gay adults, a step that, based on their surveys, they feared would cause mass defections.