The objective of this master thesis is to analyze the meaning of the party s silence under the article 111 of the Brazilian Civil Code of 2002; i.e., silence as a behavior capable of qualifying an expression of a party s will for a legal transaction, considering the legal requirements applicable thereto. The aforementioned article states that [t]he silence implies consent, when circumstances or habits and customs authorize it, and an express declaration of will is not necessary. Therefore, this work, limited to the scope of Brazilian Civil Code, seeks to clearly establish what are the assumptions for the application of silence as a legal institute, according to the legal norm that guides its interpretation in the specific case. The thesis departs from the analysis of two cases ruled by the Superior Court of Justice, in which article 111 of the Civil Code of 2002, was mentioned without observing its essential aspects. Following that, the thesis investigates the meanings of the silence element provided for in the Civil Codes of 1916 and 2002, discerning its normative content. Then, it reviews the literature of Miguel Maria de Serpa Lopes, a brazilian jurist who has developed the most complete study on meaning of silence in Civil Law, in 1937. Subsequently, the text seeks to dogmatically establish the premises to qualify the expression of will through silence, establishing its best terms and suggesting its own identity for its form. After defining the true meaning of silence provided for in article 111 of the Civil Code of 2002, this work proposes to distinguish the silence from other behavioral doctrines (i.e. mental reserve, good faith, nemo potest venire contra factum proprium, suppressio and abuse of law). In this context, several court decisions are mentioned to illustrate how the courts confuse the silence doctrine set forth in article 111 of the Civil Code with other figures of Civil Law. Finally, this dissertation clarifies the content of the assumptions necessary for the qualification of silence as a behavior capable of expressing will, to make the specific norm useful in practice.