The main objective of the article is to offer an informed answer to the question concerning which acts are relevant to determine the existence of an attack directed against any civilian population as an element of crimes against humanity according to Chilean Act Nº 20,357, as in the matter of crimes against humanity Chile has adopted a modified incorporation of the Rome Statute, and the meaning of the expression “ataque contra una población civil” is not explicitly defined. The methodology used in order to analyse this question consists of an application of the general standards of legal interpretation. As the main result, it is affirmed that in order for a relevant attack to exist, one or more acts described in Article 7.1 of the Rome Statute have to be proven, which are, as a whole, directed against a civilian population or affect a considerable number of persons. Furthermore, the act(s) shall respond to a policy from a state, or from its agents, or from organised armed groups which, under responsible command, exercise territorial control that enable them to carry out military operations, or from organised groups which hold a de-facto power that favours the impunity of their deeds.