This article gives a measure of life jacket (LJ) effectiveness in U.S. recreational boating. Using the U.S. Coast Guard's Boating Accident Report Database from 2008 to 2011, we find that LJ wear is one of the most important determinants influencing the number of recreational boating fatalities, together with the number of vessels involved, and the type and engine of the vessel(s). We estimate a decrease in the number of deceased per vessel of about 80% when the operator wears their LJs compared to when they do not. The odds of dying are 86% higher than average if the accident involves a canoe or kayak, but 80% lower than average when more than one vessel is involved in the accident and 34% lower than average when the operator involved in the accident has more than 100 hours of boating experience. Interestingly, we find that LJ effectiveness decreases significantly as the length of the boat increases and decreases slightly as water temperature increases. However, it increases slightly as the operator's age increases. We find that between 2008 and 2011, an LJ regulation that requires all operators to wear their LJs—representing a 20% increase in wear rate—would have saved 1,721 (out of 3,047) boaters or 1,234 out of 2,185 drowning victims. The same policy restricted to boats 16–30 feet in length would have saved approximately 778 victims. Finally, we find that such a policy would reduce the percentage of drowning victims compared to other causes of death.