Objective To assess life jacket use among Washington State boaters and to examine the relationship between life jacket use and boating laws.

Methods A statewide observational survey of boaters was conducted between August 2010 and September 2010. Data collection included age, sex, life jacket use, boat type, and weather and water conditions.

Results Among 5157 boaters, 30.7% wore life jackets. Life jacket use was highest among groups required by state law: personal watercraft users (96.8%), people being towed (eg, water-skiers) (95.3%) and children 0–12 years old (81.7%). Children and youth were more likely to use a life jacket if any adult in the boat wore a life jacket: 100% versus 87.2% for 0–5 years, 92.8% versus 76.7% for 6–12 years and 81.4% versus 36.1% for 13–17 years. Adult role modelling was particularly beneficial for adolescents aged 13–17 years, who were not covered by a life jacket law. In multivariable analysis, the presence of at least one adult wearing a life jacket was associated with a 20-fold increased likelihood that adolescents were also wearing a life jacket.

Conclusions Highest life jacket use was strongly associated with laws requiring use and with adult role modelling. Legislation requiring life jackets for ages 13–17 years and social marketing encouraging adult life jacket wear in the company of children and youth are promising strategies to increase life jacket use in Washington State.