Safety remains a major challenge in the construction industry throughout the world, yet there are very few longitudinal or quasi-longitudinal studies in this domain. This paper demonstrates how a quasi-longitudinal study can provide insight into safety performance. A comparison is made between two cross-sectional studies: 911 questionnaires collected from construction workers between 2004 and 2006, and 802 collected between 2014 and 2015 in Ontario, Canada. The data comprised demographic factors, 13 safety climate factors, and three safety outcome categories. Rates of injury, stress, and safety events reduced overall since 2004, although the change was significant only for events. Findings show improved consistency in safety awareness among participants independent of employers, suggesting that regionwide safety programs have been effective. Safety climate factors accounted for 15-20% of the variance in safety outcomes, down from 2004. Interpersonal conflict at work is strongly related to all safety outcome types. Participants with 11-15years of experience reported the highest safety incident rates in all categories, a trend that was not observed 10years earlier. Safety managers may consider broadening their safety programs, which often target new workers, to ensure that all workers are reminded of safe work practices. (C) 2016 American Society of Civil Engineers.