Ultrasonics are viable tools to monitor internal microstructure of polycrystalline metals. Recently, the need for such tools has dramatically increased as metallic additively manufactured (AM) materials are rapidly becoming common in engineered structures. Nondestructive techniques like X-ray CT and ultrasonics are increasingly being used as a quality control step to help assure performance. Ultrasonics can also be used to help improve and develop AM processes by integration as an in situ method to assess the relationship between part microstructure and process parameters. This presentation will cover the development of two in situ ultrasonic techniques aimed at improving the state of the art in metal AM. First, ultrasound is employed to monitor keyhole melt pool dynamics in Al6061 samples. In this application, a high-frequency ultrasonic shear wave scatters from the liquid-solid boundary of the melt pool, which allows us to monitor keyhole initiation, melt pool depth, fluctuations in depth, and solidification. The sensitivity was confirmed through ground truth measurements using simultaneous synchrotron x-ray imaging. Then, progress on using in situ diffuse ultrasonic scattering on Gr91 powder bed fusion parts will be highlighted. The microstructure sensitivity of diffuse scattering is thought to be able to discern the formation of different microstructures during the manufacturing process.