In Considerations on Representative Government, John Stuart Mill concedes that secrecy in voting is sometimes justified but, nonetheless, maintains that it should be the exception rather than the rule. This article critically examines Mill's arguments. It shows that Mill's idea of voting depends on a sharp public/private distinction which is difficult to square with democratic ideas about the different powers and responsibilities of voters and their representatives, or with legitimate differences of belief and interest amongst voters themselves. Hence, it concludes, we should reject the assumption, which many of us share with Mill, that the secret ballot is justified only on prudential grounds and recognize how central privacy is to any democratic conception of citizenship and politics.