During a news conference Tuesday morning, he announced he will step down after the next school board meeting on Thursday. He then plans to move back to Colorado to be with his wife and son.
"This was a difficult decision to make and not one made lightly. This job takes extraordinary commitment and sacrifice. But I also have a commitment to my family. It's time to rejoin them in Colorado," he said.
Chief Academic Officer Dr. Ann Smisko will serve in as acting superintendent, and Miles said he hopes she and others on his team will continue his hard work.
"I've decided now is the time I can step aside as superintendent confidently knowing that the work will continue with the leadership team in place. The team that we have assembled is committed to sustainable positive change for our students to build an even stronger better Dallas ISD for this community," he said.
Miles has been at the center of controversy almost from the day he arrived in 2012. Many were upset with his reform plans, including a teacher evaluation system and restructured system for pay raises.
There were also split opinions on the effort to overhaul DISD management and turn it into a home rule district.
A major criticism from teachers' union was that Miles didn't listen to needs of the rank and file in a district with 22,000 personnel.
Most recently, Miles fired three principals whose jobs the school board voted to save.
Union leaders say Miles' tenure has severely eroded teacher morale.
Members of the school board have moved several times to fire him.
There were reports about Miles being unhappy because the school board refused to amend his contract and give him protections in case of being fired during the next school year.
However, during Tuesday's news conference, he said he made his decision because of his family. He said the end of the school year made it a good time for a transition.
Miles' severance package is reportedly still being negotiated. He also has not yet accepted any other jobs.
"I'll take my two weeks off like everybody and then get back to work doing something," he said.
Dallas County Commissioner John Wiley Price was one of the first local leaders to react to the news.
"God is good all the time. He's set DISD back 40 years," he said.
Rena Honea, president of the local teacher's union, said she has heard a mix of reactions but said the majority of the teachers in the district are pleased to hear of Miles' department. She believes moral in the district was at an all-time low because of Miles' leadership.
He felt like that the low moral came from individual campuses; that it was not across the district," said Honea. "I beg to differ with him…it was pretty much at the low if the lows. When you're in a hole, you normally stop digging, but that didn't seem the case here."
Mayor Mike Rawlings said he is disappointed and hopes that Miles' landmark reforms will continue.
Miles sparred regularly with trustee Bernadette Nutall, even having her physically removed from Billy Dade Middle School last October.
Nutall was not present at his resignation announcement and has yet to respond to requests for comment.
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