This USGS Data Release presents major-oxide glass geochemical results from tephras erupted form Alaska volcanoes. This data set is in support of volcano hazard studies by the Alaska Volcano Observatory (AVO) where tephra (volcanic ash) deposits are used to assess eruption frequency, magnitude, and character of eruption. These data are part of a larger effort to identify and characterize tephra deposits from Alaskan volcanoes and the data set will continue to grow (versioned) as new data are generated.