Boston School Superintendent Carol R. Johnson announced Wednesday that she plans to retire this summer, ending a six-year tenure marked by historic highs on some standardized tests and graduation rates, but also some notable administrative missteps.
The announcement came a little more than six weeks after the death of Johnson’s husband, Matthew, who had been fighting a lengthy illness.
“My husband’s illness certainly impacted my thinking about how long to stay, and then, of course, the mayor’s decision not to seek reelection certainly impacted my decision as well,” Johnson said in an interview.
Nevertheless, she said, it was a difficult decision.
“I love my job, I love my work, and I love Boston,” said Johnson, who is 65.
Johnson’s retirement would occur two years before her contract is set to expire with the Boston School Committee, which has final say on ending the pact.
Michael O’Neill, the committee’s chairman, praised Johnson’s leadership and said he understood her decision to step down.
“We applaud the work she has done,” O’Neill said in an interview. “She has been a leader incredibly committed to the youth of our city.”
Launching a search for a new superintendent as the city prepares to elect a new mayor for the first time in 20 years will present challenges for the School Committee, O’Neill said. The most qualified and desirable candidates, he said, will probably be reluctant to give Boston serious consideration until it is known who the new mayor is and what that person’s vision for the school system is.
In Boston, the mayor appoints the seven-member School Committee, giving him or her considerable sway over the direction of the schools.
But Mary Tamer, a School Committee member, said it would be wise to begin the search soon, because the process can be lengthy. Boston’s last search took 18 months before Johnson was hired in 2007, and she came in after an earlier finalist abruptly withdrew when contract negotiations soured.
“It takes a good deal of time to do a proper superintendent search, and I suspect it will take us long into the fall,” Tamer said. “I would certainly expect the new mayor would have a say in the final selection process.”
In the months leading up to November’s election, Tamer and O’Neill said, the School Committee can conduct many aspects of the search, such as holding community meetings and identifying the most talented and promising candidates.
The School Committee, as it seeks a new superintendent, will appoint an interim leader. That person will oversee a huge task: the implementation of a new system of assigning students to schools closer to their homes, which will be put in place for fall 2014. Johnson recommended the adoption of that system, after it received a favorable endorsement from a special mayoral committee.
Johnson initially made her retirement announcement Wednesday morning at Mayor Thomas M. Menino’s weekly Cabinet meeting, then issued a press release and a video of herself talking about her decision. In the evening, she announced it again at a School Committee meeting.
“I’m not walking away tonight; I’ll be right here, with you, for the remainder of the school year,” she said in brief remarks at the start of the meeting. “We have a city full of passionate people who care deeply about our children. We may not always agree with them, but we can’t underestimate their commitment and their value.”
Johnson also thanked John McDonough, chief financial officer of the Boston public schools, who took over her duties while she was out of state caring for and later mourning her husband.
She said she has informally suggested that the committee appoint McDonough as interim superintendent. Committee members will begin searching for a temporary superintendent at their next meeting, on May 8.
Karen Kast-McBride, a parent of two Boston students and one alumnus, said she thought Johnson far outdid her predecessors.
“I believe Dr. Johnson has brought the most transparency and the most community involvement to the BPS in 20 years,” Kast-McBride said.
Because Johnson is initiating the departure, she will not receive any payouts for the remaining two years of the contract. She also is ineligible to receive ongoing payments from the city’s pension program, because she worked in the city for less than 10 years, and she will not be cashed out for unused sick time.
However, Johnson, who makes $267,000 annually and also receives about $56,000 toward retirement plans, is entitled to 10 days of severance pay and reimbursement for any unused vacation days. The School Department said Wednesday if did not know how many unused vacation days she had.
“Dr. Johnson has done amazing work for the children of Boston,” Menino said. “I often say that she has one of the hardest jobs in the city, and she has done it well. We are grateful for everything she has been able to accomplish for our city’s families. She leaves very big shoes to fill.”
Johnson’s announcement surprised few. Speculation over her departure has bounced around the city since last July, when dozens of parents called for her ouster after a Globe report revealed she had stood by a headmaster in 2011 after he was arrested for allegedly assaulting his wife and wrote a letter of support to a judge.
Johnson later apologized, and her supporters threw a rally for her to quell opposition.
Then Johnson’s husband, who lived in Memphis, where she previously served as superintendent, took ill in the fall, prompting her to make several trips there, sparking rumors that she would step down.
For Johnson, the retirement ends a career that spans more than four decades in public education, much of it in Minneapolis, where she served as teacher, principal, and superintendent.
In Boston, Johnson achieved notable success in bolstering academic opportunities for students across the city.
Among the accomplishments: Graduation rates have steadily increased to 65.9 percent, 14,000 more students have opportunities to participate in arts and music programs, 30 percent more students take college-level courses, and summer learning opportunities have doubled.
She also moved aggressively to overhaul 11 schools identified by the state in 2010 as underperforming, asking teachers to reapply for their jobs, which caused dozens to be reassigned.
One of the schools, Orchard Gardens K-8 in Roxbury, has turned into a national model of school turnarounds. A group of the school’s first-graders met President Obama at the White House last year and recited Martin Luther King Jr.’s “I Have a Dream” speech from memory.
But success has eluded two other underperforming schools, English High and Elihu Greenwood Leadership Academy, which could face state takeover this fall, and MCAS scores have been mixed. For instance, 10th-grade scores have been rising, while third-grade reading results have been stagnant.
Johnson’s tenure has also been marked by some missteps.
She has had a tendency to pitch proposals and then pull them back amid public backlash, such as an ill-fated plan to carve the city into five school-assignment zones and a failed proposal to relocate Boston Latin Academy.
She also struggled to get buses running on time during the two previous school years, frustrating both the School Committee and the mayor. Johnson eventually hired a new transportation director, and buses have for the most part been arriving at school on time.
Paul Grogan — president of the Boston Foundation, a charitable organization that works with the city’s schools — applauded Johnson for expanding the number of schools with extended days, adding more flexibility in hiring teachers, and trying innovative practices.
“She has left a lot for her successor to build on and to bring to the next level,” said Grogan.
Richard Stutman, Boston Teachers Union president, who frequently clashed with Johnson, said she “was a hard working superintendent who was a good listener.”
At Wednesday night’s school board meeting, Ginny Brennan of West Roxbury, mother of a Boston Arts Academy senior and a Boston Latin School alumnus, said Johnson’s appearances at school events and interactions with students impressed her.
“The first time I met her she was tapping her feet and dancing at a BLS concert, and everybody thought, ‘This is so awesome,’ ” Brennan said. “We were so excited that she was able to come.”
Earlier, Johnson said she would probably continue to work in public education after her retirement, although not as a superintendent. Her immediate priority, she said, is to finish leading the city’s school system.
“I think we have accomplished a lot of what I came to do, and I think we have made progress, but we are not perfect yet,” Johnson said.
But she added she is confident that the school system would continue to make strides after she leaves.
“I am only one person,” Johnson said, “and there are a lot of people in BPS doing fabulous work.”
Globe correspondent Gal Tziperman Lotan contributed to this report. James Vaznis can be reached at jvaznis@
globe.com. Follow him on Twitter @globevaznis. Andrew Ryan can be reached at acryan
@globe.com. Follow him on Twitter @globeandrewryan.