Complex social situations, reflected in the experiences of group members, trigger the processes of group dynamics. These processes arise specific group phenomena, which reflect such experiences. In group interaction, there are processes and states (tension, confrontation, and conflict, crisis, trauma), which affect their member to feel discomfort, stress, frustration, traumatization. As a result, the social space of interaction has a change in the dynamics of integration and differentiation processes. According to the resources available in the group (values, status in society, creative potential), it uses available at the certain moment ways of cognitive and emotional processing of a complex social situation and produces group phenomenology. Group scenarios and interaction strategies can be classified as constructive and non-constructive ones, but their evaluation depends on the out- or ingroup affiliation of the one who evaluates the interaction. According to the resources, group phenomena can perform the functions of adaptation (maladaptation) of the group to complex social situations, as well as their acting-creative overcoming. In such conditions, the group solves two tasks that, depending on the circumstances, can compete with each other: overcoming social difficulties and preserving the group as a whole. Thus, in complex situations, in accordance with the dynamics of their development in the process of group interaction unfolds a consistent emergence process of psychological phenomena chain – phenomenogenesis. The scientific novelty of the research is that in contrast to the existing models and concepts of group dynamics in psychology, the concept of phenomenogenesis takes into account the social context of group interaction, brings together the whole spectrum of group phenomena, distinguishes their functions, and defines the tasks of groups.