The tradition of tax-exempt status for nonprofit "charitable" organizations is well established, and few would argue with the principle. But the tax-exempt sector of the economy is vast and rapidly growing, resulting in the loss of billions of dollars of tax revenue. At the same time, we have no consensus on what purpose the charitable tax exemption serves, let alone agreement on what constitutes a charity. In this important addition to the theory of tax law, Colombo and Hall develop an or...