The conventional wisdom in economics, finance and law for the last fifty years has been that companies should maximize profit or market value since this is what their shareholders want. I will argue that this is wrong. In some cases companies have a comparative advantage in doing good or avoiding harm and socially minded shareholders may be willing to give up some profit for companies to do this. I will argue that shareholders can use their “voice” to push companies to be more socially responsible via voting, and that voting can achieve socially optimal outcomes under some conditions. I will also discuss how the investment landscape is changing, how shareholders are using their voice more, and how some practical problems concerning voting can be overcome.