Ensure students have stable access to high quality sources of food, shelter, medicine, friends and family. Push students to challenge their own belief systems by interacting with each other and the wider world in new and inspirational ways. Assist them in developing their introspective and creative talents. Teach students how to conquer small tasks in preparation for accomplishing larger ones.
The question is, what is meant by leadership in this context. I think many folks can think of examples (especially in HS), where the person appointed to the leadership position probably shouldn't have.
I think there are roughly two kinds of meaningful leadership, which are sometimes together and sometimes disjoint:
The best leaders are born with it, you can refine their talent but if you don't have the confidence to step up to the plate when the time comes, you will never be a leader. So kids need a framework that challenges them to accomplish things while there is a real risk of failure.