This book elaborates on drug delivery targeting via intracellular delivery, specifically through the Receptor Mediated Endocytosis (RME) approach, due to the involvement of cellular receptors in various grave diseases. Targeted delivery relies on two basic approaches, passive and active targeting. While passive targeting approaches have shown great promise, the improved selectivity achieved with active targeting approaches has resulted in significantly higher efficacy. Interestingly there are numerous strategies for active targeting, many of which are already highlighted in ,  Targeted Drug Delivery: Concepts and Applications. Nevertheless an exciting and practical strategy for active targeting, which could enable high intracellular delivery, is through exploitation of RME. Cells in the body express receptors to enable various physiological and biochemical processes. As a result, many of these receptors are overexpressed in pathological conditions, or newer receptors expressed due to d