Volume 3 of Atomic and Plasma–Material Interaction Data for Fusion is devoted to atomic collision processes of helium atoms and of beryllium and boron atoms and ions in fusion plasmas. Most of the articles included in this volume are extended versions of the contributions presented at the IAEA experts meetings on Atomic Data for Helium Beam Fusion Alpha Particle Diagnostics and on the Atomic Database for Beryllium and Boron, held in Vienna, June 1991, or have resulted from the cross-section data analyses and evaluations performed by the working groups of these meetings. The volume contains reviews of the most important classes of collision processes of plasma particles with helium atoms and beryllium and boron ions, and comprehensive sets of recommended cross-section data for these processes.