By letting more than 3,000 clients of financial institutions play an incentivized investment game, we provide field experimental evidence on the determinants of socially responsible investment decisions. Our results show a positive link between personal values, beliefs, and preferences for socially responsible investments. To better understand their investment decisions, we expose participants to four experimental manipulations. Our results suggest that how responsible funds are advertised substantially influences participants’ decisions. When individuals are able to donate to a charity prior to their investment decision, they are less likely to invest responsibly. We find that public image concerns are not an important determinant of socially responsible investments. Endorsements through ethical labels can trigger more responsible investments, but are necessary only for individuals with low beliefs in the effectiveness of social responsibility. Further, a restricted investment universe positively affects socially responsible investment allocations.