Additive manufacturing (AM) technology, also known as 3D printing, has transitioned from concepts and prototypes to part-for-part substitution and the creation of unique AM-specific part geometries. These applications are increasingly present in demanding, mission-critical fields such as medicine and aerospace, which require materials with certain thermal, stiffness, corrosion, and static loading properties. To advance in these arenas, metallic, ceramic, and polymer composite AM parts need to be free from discontinuities. The manufacturing processes have to be stable, robust, and repeatable. And the nondestructive testing (NDT) technology and inspection methods will need to be sufficiently capable and reliable to ensure that discontinuities will be detected to prevent the components from being accepted for use. As the second installment of a six-part series of SAE EDGE¿ Research Reports on AM, this one discusses the need, challenges, technologies, and opportunities for NDT in AM. NOTE: SAE EDGE¿ Research Reports are intended to identify and illuminate key issues in emerging, but still unsettled, technologies of interest to the mobility industry. The goal of SAE EDGE¿ Research Reports is to stimulate discussion and work in the hope of promoting and speeding resolution of identified issues. SAE EDGE¿ Research Reports are not intended to resolve the challenges they identify or close any topic to further scrutiny.