Additive manufacturing stands to revolutionize the aerospace design and manufacturing paradigm, driving an important need to develop certification standards for flight-ready AM components. NASA has sponsored a multi-year effort to develop a NASA standard that covers all levels of component development and criticality. It would govern hardware fabricated by selective laser melting (SLM) under sanctioned projects, including Alloy 718 components for NASA’s Space Launch System engine. The impact of feedstock variability on the microstructure and durability of SLM 718 components is being examined using 12 off-the-shelf, gas-atomized powder lots, most with standard particle size distributions (PSDs). Well-blended, representative samples from each lot were obtained for chemistry, PSD, morphology, flow, rheological properties and SEM evaluation. The major, minor, and trace elements varied within the acceptable wide ranges for Alloy 718, allowing insight into compositional space. The relationship of this suite of measurements to the as-built and post-processed properties will be outlined.