There are various descriptions out there for these stages of development. Perhaps the most famous is the so-called Boston model, and while this is also the version I like the most, it's not the one that I use the most. Instead, perhaps because I learned it first, but more likely because it is...catchy, for lack of a better word, I frequently refer back to Bruce Tuckman's stages.
Like the Boston model, Tuckman identifies five stages, which he calls: Forming, Storming, Norming, Performing, and Adjourning (see? catchy!).
Forming refers not only to the physical act of initially getting the group together and arranging logistics, but also to all the inter- and intra-personal dynamics that go along with it. People come to groups with a lot of baggage, including goals, expectations, past experiences, and related anxieties. Everyone wonders whether they will fit in, whether people will like them. They wonder if their needs will be met. They wonder who these strangers are. Therefore, forming involves a mutual process of feeling each other out, and trying to present oneself in the best possible light. People tend to be polite, but independent; the group has not yet become more than a sum of its parts.
Of course, as imperfect humans, we can only be polite and present our best sides for so long. It is inevitable that competing expectations, goals, and differences of opinion will come to light. Enter the Storming stage. In the Boston model, this stage is referred to as "Power and Control" because it often involves some degree of jockeying for position, including status and roles within the group, along with testing or challenging behavior. The group leader is frequently the target of such challenges as members test the leader's authority; one or more group members may even take over authority in the group. The group environment can feel charged, like a storm. But, while this stage is uncomfortable, it's inevitable and necessary to turn the group's parts into a cohesive whole.
Once issues of power and controol (i.e., Storming) have been resolved, the group can finally proceed to the purpose for which it was organized. However, before real progress can be made in working on that purpose, the group has to determine how it will go about its work. The group establishes a group identity and group narrative, rituals, and social norms (hence, Norming). Members are assigned or take on roles, and fall into a comfortable groove, more secure in how the group sees them, and trusting of the group dynamic as a whole. The result is a sense of cohesion.
With this foundation, the group addresses its purpose in the Performing stage. Real, tangible progress is made, and members typically feel like the group has finally begun to meet their needs or be productive. The cohesion that has developed continues, but slowly, members begin to also differentiate from the group, which makes room for the individuality of its members, including diversity of needs and interests.
Both doing the work of the group, and differentiating of individual members set the stage for the ultimate move into the group's final stage: Adjourning, also known as termination. This is a time for naming and consolidating gains, affirming the value of the group experience, and each member taking what they can from the experience for their everyday lives. The group changes back into parts as people say goodbye, but each part is still more than it was before the experience.
So, what do you think about this model? Do you see this process at work in groups you're involved with? How else do you understand the evolution of a group?