"As we prepare this revision, we are struck by how many important developments have happened in the world around us since the 15th edition. From the COVID-19 pandemic to what can seem like unprecedented social divides, our day-to-day lives feel different this time around. We worked hard in this revision to capture what some of those developments might mean for the future of effective group discussions. Our focus continues to be communication: how communication creates, maintains, and changes a group through interaction among members and with the groups environment. We encourage members and leaders to employ effective and ethical principles of communication, so their group experiences are as rewarding as they can be"--