One man everyone involved in SRI should pay attention to is David Swensen of Yale University. His performance has been exceptional - over the past 2o years the Yale Endowment's returns have been the best of any educational institution. His books, Pioneering Portfolio Management and Unconventional Success, are excellent.
This has been accomplished despite at least some social constraints. Yale has an Advisory Committee on Investor Responsibility, and during the South Africa boycott the endowment divested its holdings in companies doing business in South Africa.
Marc Gunther, a journalist at Fortune magazine and the author of the excellent Faith and Fortune, is also a Yale alum and has written this profile of Swensen for the Yale alumnae magazine. It includes commentary both on Yale's social investment policies, as well as those of other schools (notably Williams, which now has a 'Social Choice Fund' available).
Swensen is not the only investor to achieve superb results despite social constraints. Sir John Templeton, widely regarded as one of the finest investors who ever lived, avoided alcohol, tobacco, and gambling stocks for religious reasons throughout his career.