The purpose of the present study was to examine the effectiveness of a six-week intervention that aimed to promote teachers' physical activity level during working hours. Thirty-eight teachers from three intervention schools (schools randomly assigned as intervention group) received intervention prompts: SMS messages, leaflets and posters promoting walking, and a pedometer. Fourteen teachers were from a control school (school randomly assigned as control group). All participants reported pedometer readings and rated their Stage of Change scores before and after intervention. Differences in step counts per minute between groups were examined using ANCOVA adjusted by time duration for step counts. The intervention group had a higher increase in steps-at-work (t = 3.61, P less than 0.001) than the control group and type of commuter affected the increase in steps-at-work for the intervention group (F [subscript 2,34] = 4.95, P less than 0.01, eta[subscript p] [superscript 2] = 0.23). The study concluded that an intervention utilizing environmental stimuli as the strategy can be successfully applied in the school setting for the promotion of school teachers' physical activity. (Contains 1 figure and 1 table.)