This Special Issue is dedicated to all aspects of boron chemistry, including all fields of inorganic boron chemistry from oxidoborates to hydrido(hetero)borane derivatives (including boranes, carboranes, metallaboranes, and metallacarboranes), transition metal complexes of boron-containing ligands, organic and bio-organic boron chemistry (including boron-based Lewis acids, boronic acids, benzoxaboroles, aminoboranes, and the application of boron reagents in organic synthesis), boron in materials (including polymers, dendrimers, ionic liquids, liquid crystals, hydrogen storage, and catalysis), and boron in medicine (including boron neutron capture of cancer, carborane pharmacophores, boron-containing drugs, and boronic acid-based sugar sensors).