Additive manufacturing (AM) of metals is starting to revolutionize the design and production of complex, high-value metal parts. However, the extreme processing conditions of, essentially, welding millions of microscopic bits of metal together, create deleterious microstructures with high stresses, extreme compositional gradients, unexpected phases, and a variety of potentially disastrous build flaws. I will describe our work on AM Inconel 625 where we combine in situ process monitoring with laboratory, synchrotron X-ray and neutron-based measurements to validate integrated finite element, thermo-kinetic, and phase field models of the as-built and post-processed microstructures and stresses. Work on both bulk AM samples and individual laser traces will be covered. Finally, I will describe our progress in establishing the Additive Manufacturing Benchmark Test Series (AM-Bench), a continuing series of highly controlled benchmark tests for additive manufacturing that will allow modelers to test their simulations against rigorous, highly controlled additive manufacturing benchmark test data.