Objective: Group Dynamics: Theory, Research, and Practice celebrates its 25th anniversary in 2021. This special issue invited each former and current editor of the journal to reflect on a key topic of group dynamics and to provide a roadmap for current and future researchers. Method: The five former and current editors of Group Dynamics selectively reviewed the literature on a particular topic and suggested future research agendas based on the review. Results: Topics reviewed by the editors included: a unified theory of cohesion, actor-partner interdependence models, expert and lay conceptions of cooperation, the social relations model, and the synergy between reflective functioning theory and team cognition. Conclusion: These reviews by five experts in the field provide a way forward for group dynamics researchers. The reviews help define important concepts and methods that will have a scientific, social, and clinical impact for the next 25 years.
Highlights and Implications• To celebrate the 25th anniversary of Group Dynamics: Theory, Research, and Practice the previous and current editors of the journal each review a key topic in group dynamics research and provide a roadmap for the next 25 years of research in these topics.• Donelson Forsyth (2021) presents a unified theory of cohesion, an important concept for both group psychology and group psychotherapy. Forsyth argues that a clear and definitive view of cohesion is necessary to move the research forward and he presents a new psychometric scale.• Dennis Kivlighan (2021) discusses use of actor-partner interdependence models (APIM) and multilevel modeling of grouped data. He points to the need for such data modeling techniques for group researchers to truly estimate complex phenomena that occur in groups.• David Marcus (2021) reviews research so the social relations model (SRM), which is a data modeling technique. Like APIM, SRM allows group researchers to address the complex interactions and perceptions that occur in groups. He argues that SRM can be an important source of knowledge about groups.