D.C. Public Schools Chancellor Kaya Henderson will be stepping down from the system’s top spot on Sept. 30.

Mayor Muriel Bowser announced Henderson’s departure in a letter to residents on Wednesday. In it, Bowser lauded the chancellor for her near decade of service to the District’s public schools. Henderson came on in 2007 and assumed her current role in November 2010. DCPS Chief of Schools John Davis will serve as interim chancellor beginning on Oct. 1; a nationwide search—and selection process—for a new, permanent chancellor will commence in the fall, the mayor added.

“I am incredibly grateful to Kaya for her nine years of service to our students, our schools, and our city,” Bowser wrote. “Without a doubt, DCPS is a very different place today than it was when Kaya joined our school system in 2007. DCPS is the fastest improving urban school district in the country. After decades of decline, DCPS has also seen consistent, annual enrollment growth since Kaya became Chancellor—growing from 45,000 students in 2010 to nearly 49,000 students this year. While we will miss Kaya, we can all be proud of her team and her tenure as the second longest-serving leader of DCPS.”

In separate letters to parents, teachers, and principals, Henderson did not specify what’s next for her. But she said she is “ready to take on new challenges” and expressed “complete confidence” in DCPS’ present team. “I will remember the passionate and committed parents I have had the pleasure of working with,” she wrote. “While we may not have always agreed, I have always admired your dedication to your students.” To teachers and principals, she said she was optimistic that the school system’s results would keep improving through hard work.

Henderson holds one of the most lucrative positions within the D.C. government, earning more than $290,000 as annual salary. She had served as deputy to ex-Chancellor Michelle Rhee—who brought DCPS national scrutiny for her reform-driven (and sometimes controversial) ideas—before replacing her. During her current tenure, Henderson has faced a number of challenges, including more than a dozen school closures and a school-food scandal (the subject of a City Paper cover story).

Most recently, though, she became the subject of an ethics complaint over a contribution she allegedly solicited for a teacher gala. (In a statement, DCPS said Henderson and its staff had “acted lawfully and in good faith at all times.”) Teachers, meanwhile, have protested Henderson’s handling of contract negotiations. Elizabeth Davis, the president of the Washington Teachers Union, said in a statement on Wednesday night that she was “surprised” after learning about Henderson’s decision today, but “look[s] forward to completing [the] negotiations on a fair and equitable contract” soon.

“Under Chancellor Henderson, the WTU enjoyed a productive working relationship with DCPS staff and departments,” Davis said. “We expect that partnership to continue.”

The chancellor’s departure comes as the District prepares to modernize its schools over the next several years, with additional multi-million-dollar investments committed to by Bowser. It also comes as D.C. students strive to adapt to Common Core-aligned standardized tests known as the PARCC. Henderson last year called results from those tests “sobering.” Still, DCPS students have seen significant gains on a biennial federal assessment called the NAEP.

In reacting to her announced departure, some education advocates praised Henderson for her service. Catharine Bellinger, the D.C. director of PAC Democrats for Education Reform, said in a statement that Henderson has “empowered teachers and include[d] communities” throughout reforms. “The next leader of DCPS will have big shoes to fill—and will need the vision, tenacity, creativity, and humility to lead DCPS into the next phase of growth,” Bellinger said. Jack Jacobson, the president and Ward 2 representative of the State Board of Education, called Henderson a “strong partner for [SBOE’s] work.”

At-Large Councilmember David Grosso, who chairs the Council’s Committee on Education, characterized Henderson’s leadership as “visionary.”

“[I] am very proud of the work we have been able to accomplish together with a focus on equity,” Grosso said in a statement. “I have always appreciated her willingness to be open with me and her fierce advocacy, both locally and nationally, on behalf of the more than 49,000 young people enrolled in D.C. Public Schools.”

DCPS has more than 110 schools in its portfolio.

This post has been updated.