It is not possible to reduce crowd behaviour theories to a generic set of behaviours invariant of the crowd. It is important to focus on collective perceptions of the actors (1), how collective ideologies arouse people’s commitments to action (2) and the importance of actors taking on a collective identity (3).

Norm theory states that crowd events are shaped by collective norms emerging in the situation itself. This occurs in a period of milling which precedes action itself. However, it does not explain situations in which crowds act and change quickly without time for milling (1) and according to the theory the norms are formed through group interaction with prominent individuals, making the norms group-based yet individual (2).

The self-categorization theory states that defining oneself as a member of a social category is the precondition for group behaviour. This involves a process of self-stereotyping where a person attempts to conform to the standards of the group. The shift from individual to group behaviour involves a shift from personal to social identity.

Crowds usually exist in novel, ambiguous and fluid situations in which they are tasked with translating their superordinate social identity into a situational identity without formal means of doing so (e.g. formal hierarchy, debate). It is possible that crowds do this by inferring the nature of group identity from the behaviour of those seen as typical group members

The classic agitator theory states that a small group of anti-social individuals are able to take advantage of the fact that crowd members have lost their judgement in order to turn the mass to anti-social ends.

In a crowd, there are groups who adopt an ideology of non-violence and will adhere to this even when subject to extreme provocation. Only groups who see violence as potentially legitimate will be open to using violence. The concept of legitimacy determines whether a crowd will enter into conflict under any circumstances (1) and they determine the precise circumstances under which crowds who do not reject violence will enter into conflict (2).

Conflict only occurs if violence is seen as legitimate (e.g. because of an illegitimate action of the out-group) (1) and when conflict is seen as efficacious (2).

Crowd members will only enter into conflict with an outgroup where conflictual behaviour is deemed legitimate (1), outgroup action is seen to violate concepts of proper social practice (2) and conflictual tactics are considered an effective way to meet desired ends (3).

The legitimacy of the conflict (1), the concepts of proper social practice (2), identification of ends (3) and the calculation of whether these ends will be reached (4) are defined with reference to the collective beliefs of the relevant social category.

Changes in the way crowd members view themselves changes their perceptions of others. Intergroup dynamics are crucial to the onset and development of crowd conflict.

The limits of involvement in collective conflict are defined by reference to those in the crowd who perceive their rights to be denied. This is a function of the extent to which the outgroup practically differentiates between crowd members in the imposition of constraint.

The less the outgroup differentiates between crowd members, the wider the crowd’s common categorization, mutual support and feelings of empowerment in the crowd will be. This will lead to a challenge of outgroup actions. Thus, the outgroup treating the ingroup as homogeneous will lead to the ingroup acting homogeneous, supporting each other and feeling empowered.

If a powerful group reacts to the confrontational acts of one section of the crowd by denying their what other in the crowds consider to be their rights, they create conditions for that section to gain influence and for conflict to generalize as the whole crowd is involved rather than the confrontational part of the crowd.