This volume contains the proceedings of the AMS Special Session on Ends and Boundaries of Groups, held in honor of Michael Mihalik's 70th birthday, from April 15-16, 2023, at the University of Cincinnati, Cincinnati, Ohio. The papers cover current topics in geometric group theory and related topology. Four survey papers discuss hyperbolic actions, CAT(0) groups, Thompson-type groups and $Z$-set boundaries. Other papers cover new material related to hyperbolic groups, Poincare Duality groups, outer automorphism groups, right angled Artin groups, and mapping class groups. Several papers present new results on ends of spaces and related group theory. A notable addition, intended for readers interested in the interplay of topology and group theory, is a self-contained detailed exposition of $Z$-sets and their role in geometric group theory.