Purpose. The SenseWear Armband (SWA) is a multisensor activity monitor that can be used in daily life to assess an individual's physical activity level (PAL). The primary goal of this study was to analyze the impact of different types of feedback on the PAL of Flemish employees. Methods/Design. We recruited 320 sedentary employees (age, 41.0 ± 10.7 years; BMI, 26.2 ± 4.2 kg/m(2)) to participate in the 12-month study. Participants were randomized into one of four intervention groups after being measured for 7 days and nights by means of the SWA: (1) a minimal intervention group received no feedback (MIG, n = 56); (2) a pedometer group was provided only information on their daily step count (PG, n = 57); (3) a display group received feedback on calories burned, steps taken, and minutes of physical activity by means of the SWA display (DG, n = 57); (4) a coaching group also received the display and had weekly meetings with a Personal Coach (CoachG, n = 57). We hypothesize that participants receiving feedback (SG, DG, and CoachG) will have a greater increase in physical activity outcome variables compared to participants of the minimal intervention group.