HTTP cookies have been widely used for maintaining session states, personalizing, authenticating, and tracking user behaviors. Despite their importance and usefulness, cookies have raised public concerns on Internet privacy because they can be exploited by Web sites to track and build user profiles. In addition, stolen cookies may also incur security problems. However, current web browsers lack secure and convenientmechanisms for cookie management. A cookie management scheme, which is easy-to-use and has minimal privacy risk, is in great demand; but designing such a scheme is a challenge. In this paper, we introduce CookiePicker, a system that can automatically validate the usefulness of cookies from a Web site and set the cookie usage permission on behalf of users. CookiePicker helps users achieve the maximumbenefit brought by cookies, while minimizing the possible privacy and security risks. We implement CookiePicker as an extension to Firefox Web browser, and obtain promising results in the experiments.