This book presents the basic knowledge needed for becoming an effective group leader, a rationale and guide for the group leader's personal development, descriptions and examples for different types of groups that used in varying settings for a range of target audiences, and suggested skills and techniques to facilitate groups. Each chapter focuses on a major portion for the art and science of group leadership as the basic premises underlying this presentation are that there are subjects and topics that emerged from research as supportive of specific topics related to groups and group leaders, such as group developmental stages, and other topics that are more abstract and complex because these also need and rely on the inner resources and development of the group leader, such as group process commentary. The art factors provide the group leader with the expertise and knowledge for deciding when and how to intervene, helping to assist when members or the group become stuck, using the material generated in the here and now, facing the challenges of difficult members and difficult groups, constructive use of emotional intensity, conflict, and prevention of the negative impact of the leader's countertransference on members and/or on the group. Covered are becoming a group leader, group dynamics and therapeutic factors, cultural and diversity factors, ethics, professional standards and legal concerns, effective use of developmental group stages, general guidelines for planning and implementing groups, group facilitation skills, the group leader's personal development, strategies for building a therapeutic self, group challenges, difficulties and interventions: member level, and group level challenges and interventions