This work investigates time in the Brazilian culture, more specifically, the concept of punctuality. The author identified and characterized aspects of (un)punctuality as a social phenomenon shared by Brazilians who live in the city of Rio de Janeiro. The aim of this work was to detect the implicit rules in the time marking system in the city of Rio de Janeiro. The contrast between the informants´ self-perception and perception of others proved to be quite relevant since most of them think of themselves as punctual, in opposition to the generic image of unpunctuality associated with the Brazilians collectively considered. The outcomes of this research work will most certainly offer subsidies to a better understanding of the perception of punctuality among Brazilians and will enhance the thinking of teachers of Portuguese as a second language about this topic and consequently foster discussion about it in classroom activities. Considering the interdisciplinary nature of this subject, the study was carried out in the light of theoretical references in the following areas: Linguistic Anthropology, Social Anthropology, Sociology, Social Psychology, Inter-Culturalism and Cultures Crossing.