In the United States during 1999-2012, about 4 per cent of adults wore life jackets while engaged in recreation on powerboats. Educational campaigns have promoted life jacket use. Mandatory use regulations target primarily children or boaters on personal watercrafts or water skiing. We describe findings from two interventions - 'Wear It California!', a targeted marketing campaign in the California Delta region and mandatory wear regulations at four US Army Corps of Engineers (USACE) lakes in the state of Mississippi. Before the campaign in the Delta, adult wear was 8.5 per cent, increasing to 12.1 per cent during the first year, dipping to 9.4 per cent during the second year, and rising slightly to 10.5 per cent 3 plus years after the campaign. Before mandatory regulations at USACE lakes, adult wear was 13.7 per cent, increasing to 75.6 per cent during the first year, 70.1 per cent during the second year, and remaining high at 68.1 per cent in the third year. Policymakers should consider these findings when choosing how to increase life jacket use.