New Jersey education commissioner Christopher Cerf is stepping down and reuniting with Joel Klein, his old boss at the New York City Department of Education.

Cerf has led New Jersey’s schools under Gov. Chris Christie since early 2011. Now, he’ll become the top executive of a personalized learning division at Klein’s education technology company, Amplify.

“I couldn’t be more excited about Chris coming on board,” Klein said in a statement. “He’s been a classroom teacher, helped me run things in New York City Schools, and has overseen public education in one of the highest achieving states in the country.”

Cerf — a lawyer whose for-profit education sector past caused him problems when he worked for the city — who left the education department in 2009 for then-Mayor Bloomberg’s reelection campaign, where he butted heads with Bloomberg’s rival and former Board of Education president Bill Thompson. From there, he resurfaced the following March in Brazil as the head of the American arm of a Brazilian science curriculum company before Christie appointed him schools chief, with a mandate to shake up the state’s education policy.

Cerf’s departure from New Jersey’s education department comes at a time when scandal has caused Christie’s star to fade rapidly. It also means that Chiefs for Change, a coalition of state superintendents who support aggressive education policy change, is losing another member. The group released a statement today touting Cerf’s efforts to overhaul schools in Newark and Camden and his support for the Common Core standards and a tougher teacher tenure law.