On Tuesday, the chief executives of the world’s largest public companies will be receiving a letter from one of the most influential investors in the world. And what it says is likely to cause a firestorm in the corner offices of companies everywhere and a debate over social responsibility that stretches from Wall Street to Washington.

Laurence D. Fink, founder and chief executive of the investment firm BlackRock, is going to inform business leaders that their companies need to do more than make profits — they need to contribute to society as well if they want to receive the support of BlackRock.

Mr. Fink has the clout to make this kind of demand: His firm manages more than $6 trillion in investments through 401(k) plans, exchange-traded funds and mutual funds, making it the largest investor in the world, and he has an outsize influence on whether directors are voted on and off boards.

“Society is demanding that companies, both public and private, serve a social purpose,” he wrote in a draft of the letter that was shared with me. “To prosper over time, every company must not only deliver financial performance, but also show how it makes a positive contribution to society.”