Physical activity in the form of consistently opting for stair use instead of elevator use can have important health benefits. The article discusses a study assessing whether increasing the attractiveness and accessibility of a stairwell had an impact on stair use among students and employees of Maastricht University, the Netherlands. The intervention involves multiple environmental changes, including prompts and enhanced aesthetics, visibility, and accessibility of the stairwell. Stair and elevator use by students and employees of Maastricht University are observed using video cameras. Data are collected continuously during 1 week before and 4 weeks after the implementation of the intervention. A total of 21,786 observations are made. Findings reveal that total stair use increased significantly, by 8.2% and that effects remain stable over the 4-week postintervention period. Stair use can be positively and continuously influenced by improving the stairwell environment. (Contains 1 table and 1 figure.)