Numerous studies have been done on the subject since 1970s. The conculsion in most cases is that performance of funds that practice SRI is not significantly different from performance of mainstream mutual funds. However, there appear to be consistent style tilts. One study finds that SRI equity funds tend to be large-cap growth funds, another, that SRI bond funds tend to be overexposed to BBB bonds and underexposed to AAA bonds.
Also, there are differences in definitions of "social responsibility". Domini 400 Social Index excludes companies that derive any revenues from the manufacture of alcohol or tobacco products, companies that derive any revenues from gambling products or services, electric utilities with interest in nuclear power plants, and companies that derive 2 percent or more of sales from military weapons systems. Calvert Index evaluates companies based on environmental impact, workplace, product safety, international operations, human rights, community relations, and indigenous peoples' rights. Catholic funds come in at least three flavors. The least restrictive ones only avoid stocks involved with the military, abortion, and contraception. Others add pornography, tobacco, and gambling to the list of restrictions. The most restrictive ones further limit the universe by investing only in companies that, in addition to all of the above, have positive ethical scores in community, environment, and diversity.