This research into the integrity of glazing is spurred by recent accidents, including the commuter train derailment in Spuyten Duyvil, New York, on December 1, 2013. Four passengers were fatally injured in that accident. All four fatalities were attributed to ejection through window openings. Results of the accident investigation indicate that the rubber gaskets holding the window panes in place pulled out when the cars slid on their sides after leaving the track. The windows were pushed inside the cars and created openings that allowed occupants to be ejected. After its investigation, the National Transportation Safety Board issued a recommendation for more-effective passenger containment by glazing systems in derailments. In addition to functioning as windows, glazing systems are also expected to be impact resistant, to provide emergency egress and emergency access, to be fire resistant, and to provide occupant containment. Research activities include assessing the performance of current glazing systems in meeting all expectations, especially occupant containment, developing modifications for improving safety performance, and comparing the performance of conventional and modified glazing systems. The objective of the Federal Railroad Administration’s (FRA’s) research into the integrity of glazing is to describe comprehensively all the engineering requirements placed on glazing systems and to develop effective strategies for balancing all the safety demands. The integrity of glazing is one of many research topics on the crashworthiness of rail equipment and is conducted by FRA in coordination with other topics, such as the integrity of the side structures of passenger equipment and the protection of occupants.