As administrator of Medicare and Medicaid, Donald Berwick has been in charge of paying for the health care of nearly one in three Americans. He has also had an important role in implementing last year’s health reform law, which uses the Medicare system as a big lever to change how doctors and hospitals do business, in hopes of containing costs.

Before taking the job — which he’ll leave in early December — the Harvard-trained pediatrician was a leading advocate for quality and patient safety, and often a blunt critic of our health system.

Berwick’s nomination faced opposition from conservatives who focused on, among other things, his praise of government-run British health care. Instead of being confirmed by the Senate, Berwick was given a temporary ‘recess’ appointment by President Obama, which was scheduled to run out this year.

He spoke to MONEY writer Amanda Gengler in October, as a special congressional committee was debating cuts to Medicare and Medicaid; the interview has been edited.

Long before you took over Medicare and Medicaid, you described the health care system as ‘unraveling.’ What did you mean by that?

We have in some sense a miraculous health care system.

When I was training as a young pediatrician, many children died […]