This report presents the results and conclusions from the ambient air monitoring conducted as part of the 2012 National Monitoring Programs (NATTS, UATMP, and CSATAM) - three individual programs with different goals, but together result in a better understanding and appreciation of the nature and extent of toxic air pollution. The 2012 NMP includes data from samples collected at 64 monitoring sites that collected 24-hour air samples, typically on a 1-in-6 or 1-in-12 day schedule. Thirty sites sampled for 59 volatile organic compounds (VOCs); 37 sites sampled for 15 carbonyl compounds; eight sites sampled for 80 speciated nonmethane organic compounds (SNMOCs); 25 sites sampled for 22 polycyclic aromatic hydrocarbons (PAHs); 19 sites sampled for 11 metals; and 25 sites sampled for hexavalent chromium. Over 233,000 ambient air concentrations were measured during the 2012 NMP. This report uses various graphical, numerical, and statistical analyses to put the vast amount of ambient air monitoring data collected into perspective. Not surprisingly, the ambient air concentrations measured during the program varied significantly from city-to-city and from season-to-season. The ambient air monitoring data collected during the 2012 NMP serve a wide range of purposes. Not only do these data characterize the nature and extent of air pollution close to the 64 individual monitoring sites participating in these programs, but they also identify trends and patterns that may be common to urban and rural environments and across the country. Therefore, this report presents results that are specific to particular monitoring locations and presents other results that are common to all environments. The results presented provide additional insight into the complex nature of air pollution. The raw data are included in the appendices of this report.