Method: A 24-week experiment was conducted to assess how first aid training affects the motivation of small business construction industry employees in avoiding occupational injuries and illnesses and its effect on their occupational health and safety behavior. A simplified multiple baseline design across workplace settings was used to evaluate the effects of first aid training. Participants' motivation to control occupational safety and health risks was explored during in-depth interviews before and after receipt of first aid training. Objective measurement of occupational safety and health behavior was conducted by a researcher directly observing the workplace before and after participants received first aid training. Results: The observations at participants' worksites suggested that, for the most part, the first aid training had a positive effect on the occupational safety and health behavior of participants. First aid training appeared to reduce participants' "self-other" bias, making them more aware that their own experience of occupational safety and health risks is not beyond their control but that their own behavior is an important factor in the avoidance of occupational injury and illness