To improve hospital performance in door-to-balloon (DTB) times nationally, the American College of Cardiology D2B Alliance recently enrolled approximately 1,000 hospitals that perform percutaneous coronary intervention (PCI) across the United States in a large national quality improvement effort. We evaluated recent changes in DTB times in hospitals within the Get-With-The-Guidelines (GWTG) Coronary Artery Disease (CAD) program, a partner in the D2B Alliance. Within GWTG-CAD participating hospitals, we studied DTB in nontransferred patients with ST-elevation myocardial infarction treated with primary PCI from July 2006 to March 2008. We evaluated the percentage of patients treated within 90 minutes and used multivariable models with generalized estimating equations to examine trends over time after accounting for changes in patients' characteristics. A total of 5,801 patients at 167 hospitals were included in our analysis, with 3,567 patients at 98 hospitals that joined the D2B Alliance. From July to September 2006, 54.1% of patients received primary PCI within 90 minutes. This number increased significantly during the study period: 335 (74.1%) of 452 patients at GWTG-CAD participating hospitals were treated within 90 minutes from January to March 2008, including 229 of 304 patients (75.3%) treated at hospitals that joined the D2B Alliance and 106 of 148 patients (71.6%) treated at other GWTG-CAD participating hospitals (p <0.001 for all comparisons over time). No statistically significant differences were noted in the rate of change between hospitals that joined the D2B Alliance and other GWTG-CAD participating hospitals. In conclusion, the percentage of patients treated with 90 minutes has dramatically increased at hospitals participating within the GWTG-CAD program, coinciding with the launch of the D2B Alliance. These improvements were broad and not limited to hospitals that joined the D2B Alliance.