This report covers one portion of a research project to evaluate existing National Fallout Shelter Survey (NFSS) structures for resistance to combined nuclear weapons effects. The objective of the investigation was to determine the respons of windows to air blast overpressures generated by nuclear explosions, including glass fragment characteristics (weights, velocities, numbers produced, and spatial densities) that could be used to predict statistically the effects of window glass failure on humans. The analysis leading to the presentation of graphs, which can be used to predict. the free-field overpressure at incipient failure for sheet and plate glass, was based on the theoretical load-deflection equation for large deflections of plates, modified by test results found in the literature. Glass panea were changed to equivalent single-degree-of-freedom systems in the analysis was also used to estimate the time to failure lor windows at various overpressures. Methods for predicting glass fragment characteristics were obtained empirically from Operation Teapot nuclear test data. The procedures for estimating incipient failure overpresssures and fragment weights, spatial densities, numbers, and velocities were applied to windows in 14 buildings (located in San Jose and Palo Alto, California) that were part of the NFSS.