This work reviews the current state of the art in metallic microlattice structures, manufactured using the additive manufacturing processes of selective laser melting, electron beam melting, binder jetting and photopolymer wave guides. The emphasis is on structural performance (stiffness, strength and collapse). The field of additively manufactured metallic microlattice structures is fast changing and wide ranging, and is being driven by developments in manufacturing processes. This book takes a number of specific structural applications, viz. sandwich beams and panels, and energy absorbers, and a number of conventional metallic materials, and discusses the use of additive manufactured metallic microlattice structures to improve and enhance these structural performances. Structural performances considered includes such non linear effects as plasticity, material rupture, elastic and plastic instabilities, and impact loading. The specific discussions are put into the context of wider issues, such as the effects of realisation processes, the effects of structural scale, use of sophisticated analysis and synthesis methodologies, and the application of existing (conventional) structural theories. In this way, the specific discussions are put into the context of the emerging general fields of Architectured (Architected) Materials and Mechanical Metamaterials.