Construction industry is one of the most dangerous industries, not only in the USA, but worldwide. In this longitudinal study we examined the effects of safety initiatives on the safety performance of construction companies. One of the measures commonly used in the USA to track a company's safety performance is the experience modification rate (EMR). The EMR is based on the company's safety records (injury claims) from the past three full years and is used to calculate the workers' compensation insurance premiums. In a longitudinal study, we studied the effects of safety efforts and initiatives on the EMR. The results show that safety initiatives and money spent on safety do improve safety performance, but only over time.