Nano- or micro-encapsulation is used in many different fields and industries, including pharmaceuticals, cosmetics, food, and agrochemicals. It offers advantages for various applications, especially drug delivery. Nano-encapsulation can help extend and control the release of drugs as well as increase drug bioavailability and efficacy. It improves the precision of targeted drug delivery and allows for fabricating nano-encapsulated drugs for diagnostic and theranaostic applications. This book covers recent advances in fabricating nano-/micro-capsules using natural carriers for therapeutic and diagnostic drug delivery applications as well as rheology and formulations of micro-emulsions for diverse applications. This book is essential for scientists and researchers with diverse backgrounds in chemistry, engineering, material sciences, pharmaceuticals, and drug delivery.