The objective of the study was to compare national and state-level estimates of self-reported and observed seatbelt use for 2008. Self-reported seatbelt use from the 2008 Behavioral Risk Factor Surveillance System was compared with 2008 observed seatbelt use published by the National Highway Traffic Safety Administration. The ratio of self-reported belt use to observed use was calculated for each state, and the correlation between the two seatbelt measures was examined using the Pearson correlation coefficient. The median state ratio of self-reported to observed belt use was 0.97. Self-reported use was lower than observed use in 38 states. A moderate association was revealed between the self-reported and observed use (r=0.71, p<0.01). The findings suggest that, as seatbelt use has increased over time, measures of self-reported and observed use have converged, and any upward bias in self-reported use due to social desirability has substantially declined.