Washington, D.C., marked the end — and the beginning — of an era this weekend when the Boy Scouts of America established its first all-girl troops in the nation’s capital.

Now known as Scouts BSA, the organization — which celebrates its 109th birthday on Friday — has begun welcoming girls in a rebranding effort amid dwindling membership, sex abuse scandals and criticism from the equally venerable Girl Scouts of the USA.

In the District, nearly 30 troops with an estimated 200 girls took the Scout pledge on Saturday. Across the country, thousands of girls have entered the scouting program since Friday, becoming eligible to achieve the rank of Eagle Scout — a distinction that signifies years of participation and success in leadership, civic duty and self-reliance.

“Our goal is to help families instill confidence and good judgment in these young girls,” said Craig Burkhardt, the scoutmaster for the District’s newly formed Scouts BSA Troop 248, which held its inauguration ceremony Saturday.

For Caroline Hurley of the District, an inclusive Boy Scouts allows both of her 13-year-old twins, a boy and a girl, to be in the program, albeit in separate troops. It also provides weekend activities that her daughter lost when the local Girl Scout program disbanded.

“We had witnessed this wonderful scouting program for my son … and heard on the news that the Boy Scouts program would be expanding and opening up to girls,” Ms. Hurley said. “My daughter was right on it. She wanted to join the minute she heard the news.”

Dressed in their official khaki shirts and forest green hats with orange insignia, several members of Troop 248 expressed excitement at being the first to join Scouts BSA.

“It brings unity to the female gender,” said 11-year-old Tatiana Johnson, whose shirt also made a statement, reading: “Anything boys can do girls can do better.”

Founded on Feb. 8, 1910, the Boy Scouts of America was an outgrowth of a new movement of outdoor adventure training for boys in England. The Girl Scouts was founded two years later, and the two organizations always have been separate.

When the Boy Scouts announced in October 2017 that it would begin admitting girls, the Girl Scouts issued a searing statement accusing the organization of ignoring fundamental problems of corruption and sexual assault within the group and covering it up with an attempt at inclusion.

“The Boy Scouts’ house is on fire,” the Girl Scouts said in the statement. “Instead of addressing systemic issues of continuing sexual assault, financial mismanagement and deficient programming, BSA’s senior management wants to add an accelerant to the house fire by recruiting girls.”

In November, the Girl Scouts filed a trademark infringement lawsuit against the Boy Scouts for dropping “Boy” from its rebranded Scouts BSA.

The Girl Scouts argues that the name change confuses parents and families who believe the two organizations have merged and threatens to marginalize the Girl Scout activities and that Scouts BSA can’t claim a monopoly on the word “Scout” or “Scouts.”

The Scouts BSA has about 2.3 million registered members, down from the organization’s peak of about 5 million members in the 1970s.

Decades of scandals have bruised the image of the scouting group. In 1991, The Washington Times first reported in a five-part series about endemic sexual abuse and cover-ups within the Boy Scouts, accusations dating back to the 1970s and evidence of cover-ups since the founding years. Lawsuits brought by abused current and former members shed light on scores of predator Scout leaders.

In the late 1980s, the organization implemented a “Youth Protection Program” to train scoutmasters and parents to recognize potentially threatening or dangerous behavior and ways to respond and report.

In 2013, the organization ended its ban on openly gay Scouts and two years later its ban on openly gay leaders.

Since the late 1960s, girls have been able to participate in the Boy Scouts via programs such as the Sea Scouts and Venture Scouts.

By allowing girls ages 11 to 17 into Scouts BSA, the organization said, it is responding to a request by families who wanted their daughters to have the same experience as their sons. No Scout troops are co-ed, and girl troops are led by women as well as men.

On Saturday, parents of Troop 248 members said they had little knowledge of Scouts BSA as a whole until they started hearing about a movement to start a troop.

“They did Girl Scouts when they were small,” Elizabeth Neal said of her two daughters, who are among the founding members of Troop 248. “But they’re excited about camping and outdoor skills. That’s what drew them to Boy Scouts, and they’re excited about the potential to be an eagle scout.”

Parents said the new troop provides weekend activities and new friends, as well as opportunities to instill leadership, teamwork and independence in their daughters.

“It’s a good story for our region. It’s bringing out something positive for our community,” said Allison Johnson, the mother of 11-year-old Tatiana.

Troop 248 will meet twice a month, one indoor activity and one outdoor. Leaders will organize speakers from the community, with an emphasis on women in leading roles in business and community, in addition to teaching the lessons of the “Scouts BSA Handbook.”

“The whole purpose of this thing is not to teach kids how to camp or tie knots — that’s a wonderful thing — but Scouting is about helping families, about instilling leadership and good judgment and good citizenship in their children,” said Mr. Burkhardt, who is in charge of programming and leadership for Troop 248. “The Boy Scouts, BSA, has used the outdoors as the classroom in an effective way, and these girls are interested in being in the outdoors.”