Interest has been increasing in studying various sources of volcanic ash in concrete, due to the possible environmental and economic impacts. Of specific note to South Central is the volcanic ash from the eruption of Mt. Mazama. The use of this material on a larger scale could result in noticeable cost savings from refinement and transport of the material locally, in addition to reduced carbon outputs. Volcanic ash has long been used as a substitute for cement in concrete since as early as ancient Greece and Rome. Since then, its use has been extensively studied throughout the world, but due to the high variability of the ash between volcanos, as well as between differing locations of ashfall from the same volcano, its use has been hindered until studied. This report presents the results of laboratory tests conducted on Mt. Mazama volcanic ash obtained from Beaver Pumice in Klamath County, Oregon. Included in this report are sieve gradation analysis, sample specific gravity, mortar strength activity index, and concrete cylinder compressive strength testing. The findings reveal the useful and promising nature of Mazama ash as a supplementary cementitious material. For both concrete cylinder compressive strength testing and strength activity index (SAI) testing, Mazama replacement samples were under 75% of control strength, but surpassed this value at later testing days such as 56-day and 90-day. Future research on the material is necessary before use at an industrial scale.