We examine whether directors' and officers' (D&O) liability insurance affects a firm's cost of equity. We find a positive association between D&O insurance and the cost of equity. Information quality and risk-taking appear to be two underlying channels through which D&O insurance affects the cost of equity. Further tests suggest that this positive association is not due to optimal risk-taking, as evidenced by a negative market reaction to an increase in D&O insurance coverage, a lack of improvement in firms' cash flow and a low valuation associated with D&O insurance. Overall, our evidence is consistent with the notion that D&O insurance weakens the disciplining effect of shareholder litigation, leading to an increase in the cost of equity.We thank S.P. Kothari (the editor) and an anonymous reviewer for many insightful comments and suggestions. We also thank