Lyft’s co-founders in the coming months will depart their executive positions, the company announced Monday. CEO Logan Green on April 17 will transition to chair of the Lyft board, when David Risher, a current Lyft board member, will assume the chief executive role. President John Zimmer on June 30 will depart his position and become vice chair of the Lyft board. Green and Zimmer founded Lyft in 2012.

Risher since November 2009 has been CEO of Worldreader, a nonprofit he co-founded that promotes childhood reading. Prior to that, he served as SVP of U.S. retail for Amazon, where he was the 37th employee, according to Lyft. He also previously was a general manager at Microsoft.