If you agree to take part in this study, you will be asked to complete several questionnaires. These questionnaires will ask about your feelings and moods, thoughts about smoking, risks of smoking, smoking history, and basic information, such as your age, education level, and income level. The questionnaires will take about 30 minutes to complete. You will also complete a breath test. To complete the breath test, you will blow into a tube that's attached to a machine about the size of a pocket computer. The breath test is used to estimate the amount of tobacco smoke that you inhale.