Crowd psychology is a phenomenon that is understood to be part of the broader study of social psychology. The basic concept of crowd psychology is that the thought processes and behavior patterns of the individual often vary from those of a larger group, although these same individuals often adapt to the expectations of the surrounding culture and modify individual traits in order to identify with the crowd. Different theories of crowd psychology focus on both the conscious and subconscious ways that individuals align with the crowd mentality.

The convergence theory as applied to crowd psychology is that the behavior of the crowd takes on focus and form based on the input of the individuals who make up the group. Within the framework of this type of crowd psychology, persons who wish to become part of the existing group will make a choice to identify with the prevailing mindset. In some cases, this may mean minimizing or abandoning behaviors or beliefs that are not in harmony with the majority.

However, change may take place in the group over time, due to the inclusion of new people who identify with part of the beliefs and behaviors of the group, but who also bring new concepts into the group with them. As groups of people assimilate these new ideas, the overall culture of the group changes. This is a process that can take long periods of time, and for many years may be so subtle that even the most traditional members of the group may be unaware of the incremental rate of change.

The Emergent-Norm approach to crowd psychology affirms that crowds are collections of individuals who usually come together around a foundation of connected understandings, but still retain many of their individual traits. It is the expression of these individual traits that can be picked up on by other members of the community, and eventually become part of the overall mindset of the group. In this process, different members take on roles within the society, with some emerging as leaders, while others become managers and still others as active followers. Within each group psychology, there are those that remain passive and tend to go along with the majority. The roles are not carved in stone, so it is possible for an individual to function as a leader at one point, and later modify his or her expression to that of a follower or manager.

As with any psychology theory, there are a number of other approaches to crowd psychology that tend to assign responsibility for group dynamics and individual reactions to a wide variety of situations and motivations. There is still a great deal of controversy about whether groups of people influence the individual or whether acting collectively is the result of choices made by individuals. With some merit and plenty of examples to illustrate each approach, crowd psychology will continue to be an exciting area of study for many years to come.