Additive Manufacturing or Direct Manufacturing, popularly known as 3D Printing, has become the leading-edge manufacturing technology. Today Metal Additive Manufacturing (MAM) is a reality, not only for prototype fabrication, also for functional parts in all industrial sectors. Design freedom that the AM processes offer has led to design and engineering of new, complex, light-weight structures in all applications. However, in order to realize further and widespread use of metal AM for manufacturing critical components, it is necessary to explore the inherent material freedom in AM. While new metal AM materials are being developed, the role of Materials Science and Engineering (MSE) is becoming more apparent than ever before. This presentation will highlight the increasing role of Materials Science and Engineering in metal AM technologies. This presentation will show the essence of metallurgical principles in realizing full scope of material freedom in metal additive manufacturing. This presentation will demonstrate how fundamental MSE principles can be utilized to develop new materials, optimize metal AM and post processing, and their controls that cannot be achieved by conventional manufacturing methods. The examples with new Aluminum AM alloys will be presented, leading to a path of developing advanced and higher performance products for critical applications.