The purpose of this first chapter is to introduce the content of the book “Nanoparticles & Catalysis: Advances in Synthesis and Applications.” As suggested by the title, this book is fully dedicated to the new trends in research addressing the engineering of metal nanoparticles for their application in the field of catalysis. After general information on the position, interests, and perspectives of this overgrowing domain, that is nanocatalysis, a short overview of the 15 chapters gathered is provided. The so-assembled data cover different domains of nanocatalysis both in terms of the nature of the nanocatalysts developed (metal nanoparticles or derived composite materials) and the variety of catalyses and reaction media studied. The reported applications deal with either nanocatalysis in solution conditions or in the supported ones. The readers from academic or industrial communities will find in this book a basic knowledge on the recent advances in the design of well-defined and efficient nanocatalysts by taking advantage of diverse synthesis methods and materials. This collection of chapters well illustrates the research efforts presently done in order to not only reach higher and original performances but also a better understanding of the key parameters for nanocatalysis.