I was never formally a student of Joel’s but learned about philanthropic strategy from him when the AVI CHAI Foundation, where I was then North American executive director, engaged him to track and report to the field on the organization’s plan to spend down its assets. The ultimate success of AVI CHAI’s spend-down is due in large part to the foundation’s embrace of Joel’s critique and the revamping of our philanthropic approach. Joel’s answer, as spelled out in his 2007 book, “The Foundation: A Great American Secret; How Private Wealth Is Changing the World ,” is that the tax treatment of foundations gives them a unique competitive advantage over other sectors.