Dynamic security questions. In an embodiment of the invention, a security question and one or more rules for generating an answer to the security question are received. The security question and the rules for generating and answer to the security question are associated with security credentials of a user. For authentication, a first answer to a security question associated with a user is received. One or more rules for generating an answer to the security question are retrieved. A second answer to the security question is generated, based on the retrieved rules. The first answer is compared with the second answer, and the user is authenticated, based on the first answer matching the second answer.