The chemistry that occurs within confined spaces is the product of a collection of forces, often beyond the molecule, and is not easily ascribed to singular factors. There is a breadth of material types that can define a confined space (e.g. macrocycles, interlocked molecules, porous and non-porous crystals, organic and inorganic/coordination cages) which are rarely discussed together. Studies of supramolecular entities in the solution and solid states are also not often compared in the same discussion, even though the concepts are often similar or can be easily transferred between the two. Chapters in this book combine classical host-guest chemistry with catalysis, reactivity, and modern supramolecular chemistry. They cover the many different technologies used to describe and understand reactivity in confined spaces in one accessible title. With contributions from leading experts, Reactivity in Confined Spaces will be relevant for graduate students and researchers working in supramolecular chemistry, both organic- and inorganic-based, homogeneous and heterogeneous catalysis, polymer chemistry, and materials science in general.