Though the Mormon Church has no official policy against women wearing pants to church, many say they feel peer pressure to wear a dress, particularly in the Western United States, organizers said. So on Sunday, thousands of Mormon women arrived at church in pants in places like Cambridge, England; Heidelberg, Germany; Austin, Tex.; the Marshall Islands; and Kotzebue, Alaska. A number of the women posted their photos on Facebook and other Web sites. Others said they could not participate because they were fearful of ridicule or reprimand.

A Google map, begun so women could show they participated, included posts like this one, from Kari White, in Sheboygan, Wis.: “felt free to be an authentic me for the first time in my nearly 5 years of membership in the church.”

Joanna Brooks, a professor at San Diego State University and the author of “The Book of Mormon Girl: A Memoir of an American Faith,” called it “the largest concerted Mormon feminist effort in history.”

A church spokesman, Eric Hawkins, declined to comment on the event.

Organizers hope the dialogue will now expand to include issues like the ordination of women, or women taking on more responsibilities at church events.

They also cited the pronounced role of the Boy Scouts in the church — boys routinely become troop leaders in the organization, but girls have no similar outlet with the Girl Scouts — and the fact that young men are required to go on two-year missions to spread the faith, but young women are not. The result: the vast majority of Mormon missionaries are men.

“Wear Pants to Church” was the idea of Stephanie Lauritzen of Salt Lake City. She and some fellow Mormon women who belonged to a group called All Enlisted posted an events page on Facebook on Dec. 9. Within days, thousands had pledged their support, but one person threatened to shoot women who showed up in pants. Ms. Lauritzen, 26, also received threats on her own Facebook page that are being investigated by Facebook and the local authorities, she said.

On Dec. 11, the Salt Lake City-based church leadership issued a statement: “Generally church members are encouraged to wear their best clothing as a sign of respect for the Savior, but we don’t counsel people beyond that.”

The All Enlisted “friends” page has drawn hundreds of posts, both for and against the idea. JoEllen Swarts of Las Vegas wrote: “What is wrong with all you women??? If you’re not happy with the LDS church, move on, find another place of worship. You will not change Mormon Doctrine.”

At a suburban church in Green Valley, Nev., less than 10 miles from the Las Vegas Strip, women filed into church on Sunday morning, most wearing dresses (most men wore coats and ties). Bishop Michael Durham was somewhat dismissive of the pants idea. “I think wearing pants is not liberating,” he said. “Liberation comes from inside. I’m not sure they have a clear understanding of the church’s position on gender.”

Soraya Cordeiro said she wore pants because she had to take a long bus ride to her job at the Venetian hotel after church and found wearing a dress to be “a hassle.” She said she had never faced rebuke for her choice of attire.

On Monday, a private All Enlisted Facebook page had collected about the same number of “negative experiences” as “positive experiences” from women across the country. Julie Tuovi Baker Hansen, a lawyer in Burbank, Calif., who participated while visiting a Salt Lake City suburb, said she was surprised to see a man raise his hand and say, “Women who want to wear pants, they just don’t know how to follow the Lord.”

Ms. Hansen, the only woman wearing pants in a room of about 50 people, said she felt “pretty irritated.”

Aimee Hickman, the editor of a Mormon feminist magazine called Exponent II, said she originally had reservations about the event. But then she saw the negative reaction by church members online. “This made me rethink my original position,” Ms. Hickman said. The attention drawn to the effort, she added, “has people talking about Mormon gender roles more than anything I’ve seen.”