Participation in this open-label, observational study will last approximately 1 to 2 weeks, and will consist of two to three study visits. The first visit will last about 2 hours, and will include screening procedures, completion of baseline questionnaires, and a practice session of smoking topography. Subjects will return on a second day (Day 2) for the remainder of the study procedures to assess their smoking puffing behavior and nicotine intake from usual cigarette smoking, which will occur within 1 week of the Day 1 assessments. On the afternoon prior to Day 2 subjects will have a brief appointment to review instructions for using the topography device. They will take the topography with them and be instructed to use it as they smoke ad-lib that evening at home. This will serve as a second practice session for getting used to the topography device. They will also be instructed to use the device for all cigarettes smoked upon awakening the next day at 6am (Day 2), including the first cigarette of the day. They will go to the study site for the first of three blood tests at 9:30 A.M, after which they will be allowed to leave the study site to continue with their daily activities. They will use the smoking topography device throughout the day, until 3 P.M. At this time, study staff will go to each participant's location to collect the device. Participants will have two additional blood tests over the course of the study to measure nicotine levels.