Deviations from the area law for supersymmetric black holes

We review modifications of the Bekenstein-Hawking area law for black hole e ntropy in the presence of higher-derivative interactions. In four-dimension al N = 2 compactifications of string theory or M-theory these modifications are crucial for finding agreement between the macroscopic entropy obtained from supergravity and the microscopic entropy obtained by counting states in string or M-theory. Our discussion is based on the effective Wilsonian a ction, which in the context of iii = 2 supersymmetric theories is defined i n terms, of holomorphic quantities. At the end we briefly indicate how to i ncorporate non-holomorphic corrections.