We propose to conduct a randomized study of standard behavioral weight-loss treatment to test if using an electronic diary with or without tailored feedback will improve adherence to self-monitoring and subsequently improve weight loss. Subjects will be randomly assigned to different methods to self-monitor food and exercise habits: (1) use of the traditional paper diary , (2) use of a personal digital assistant (PDA), or (3) use of a personal digital assistant that also provides daily feedback.