What do we know about non-profit boards?

In fact, however, a reasonable consensus of experts on NPOs [non-profit organizations] agrees that their governance is generally abysmal, worse than that of for-profit corporations.  NPO directors are mostly ill-informed, quarrelsome, clueless about their proper role, and dominated by the CEO — as proponents of shareholder primacy would predict.

Here is the full paper by George W. Dent, Jr.  Here is the more general literature.