An evaluation was conducted on the results of the Certified Safe Farm controlled intervention program on a wide range of occupational health and safety outcomes. This report focuses on the outcomes of personal protective equipment (PPE) usage among one cohort of 438 Iowa (owner-operator) farmers in the Certified Safe Farm study during a 5-year period from 2004 to 2008. Intervention farmers reported an 11% increase in regular respirator usage and a 23% increase in regular use of hearing protection relative to comparison groups. Furthermore, it was revealed that personal factors such as smoking and low self-assessment of health status are associated with lower usage of PPE. The authors provide evidence that multiple modalities of intervention are more likely to affect safe behavior changes in the owner-operator farming population compared with single modality interventions. Further, farmers reported that personal factors such as smoking history and low self-assessment of health status are associated with lower usage of PPE.