The chief executive and founder of the charity that runs the National Citizen Service is to step down next year.
Michael Lynas, who helped set up the NCS in 2009 and became the first chief executive of the NCS Trust in 2013, said he had decided to seek new challenges.
He will remain a patron of the charity and will remain in post until spring or summer 2020 while a new chief executive is recruited.
Under his guidance, the NCS has been given royal charter status and receives more than £180m in government funding each year.
Lynas said in a statement about his departure that leading the NCS had been "the privilege of my life" and its programmes had helped almost 600,000 young people.
"Just as I am ready for my next challenge, NCS is now ready for its next decade," he said.
"The NCS is a life-long passion for me and, while I am proud to hand the NCS on to my successor in great shape in 2020, I will continue to champion the values and mission of the NCS Trust as founder and patron."
Brett Wigdortz, chair of the NCS Trust, said: "Michael’s passion has not only brought a new idea into the world, but allowed it to flourish as something amazing.
"On behalf of everyone at the NCS Trust, I would like to thank him for his leadership and for continuing to serve into 2020 while we select the right person to lead the second decade of the NCS."
David Cameron, the former Prime Minister and chair of NCS Patrons, said the NCS "would not exist today" without Lynas.
"Since 2009, he has worked tirelessly to bring it to life both inside and outside government," Cameron said.
"NCS is one of the things that I am most proud of during my time as Prime Minister because it makes such a tangible difference to young people’s lives. Michael’s public service has helped to establish a new national institution, an achievement of which he should be justifiably proud."