Nanotechnology has revolutionized the approach to designing and developing novel drug delivery systems. The last two decades have seen a great interest in the use of nanotechnology to offer efficient ways of delivering new and existing drugs and macromolecules. The focus of this book is the application of nanotechnology to deliver drugs and biological agents by the mucosal routes of administration i.e. nasal, pulmonary, buccal, and oral routes. It provides an overview of nanotechnology in drug delivery with a description of different types of nanoparticles, methods of preparation and characterization, and functionalization for site-specific drug delivery. The emphasis is on the use of nanoparticles in treating various cancers and infectious diseases. It broadens the use of nanoparticles by including biologics, including vaccines and immunotherapies, apart from drugs and acknowledges the concerns around the potential toxicity of nanoparticles to the host; several chapters will discuss the biodistribution of these nanoparticles when mucosal routes of administration are employed. Further, the interaction of nanoparticles with the host’s immune cells is discussed. Moreover, it reviews the regulatory aspects of nanotechnology in product development, especially when delivered by the mucosal route of administration. Lastly, discusses the challenges and opportunities to manufacture nanoparticles on an industrial scale. This book is the first of its kind to focus on the design, development and delivery of nanoparticles when administered by different mucosal routes.