This section proposes the construction of key concepts in analysing the problem of gender-based violence, differentiating the latter term from domestic violence. Gender is a social construction, a set of traits assigned to men and women in a society, acquired and naturalised through socialisation and sensation processes that create roles as social expectations of behaviour. The contagion/imitation effect is the repetition of acts or acts by imitation, which are previously depicted by a similar one. As a result of various cultural causes involved and social stimulations, the frequency of their transfer from one person to another as contagion is pointed out. The proposal is to refer to this effect, as a dual phenomenon ‘contagion — imitation’: this is the reproduction of behaviour of gender-based violence that resembles a previous one, in some cases as a pattern.