Well, without it, you could easily be engaged in litigation down the road. By way of example, without an agreement in place, the shares of a deceased shareholder will vest in that shareholder’s heirs, who will then be able to review the corporation’s books and vote. If that person doesn’t understand what’s best for the corporation, then eventually you could find yourself dissolving the corporation and selling the business. Like with Operating Agreements, you do not “need” a Shareholders Agreement. That is, there is no law requiring it. But entering into a business relationship with other shareholders without a Shareholders Agreement exposes you, your fellow shareholders, and the business, to significant risk.