Additive manufacturing has the potential to fundamentally change the production and distribution of goods. Unlike conventional or subtractive manufacturing processes, such as drilling, which create a part by cutting away material, additive manufacturing builds a part using a layer-by-layer process. Additive manufacturing has been used as a design and prototyping tool, but the focus of additive manufacturing is now shifting to the direct production of functional parts -- parts that accomplish one or more functions, such as medical implants or aircraft engine parts -- that are ready for distribution and sale. This book discusses the use of additive manufacturing to directly produce functional parts, including its opportunities, key challenges, and key considerations for any policy actions that could affect its future use. This book explores the development and application of additive manufacturing as well as initiatives in the United States and other countries to advance it. It also examines the technology's effect on firm and industry production activities, as well as the potential implications for U.S. manufacturing competitiveness focused in three industries.