Studies combining psychology and political science have shown that personality traits such as extroversion and openness to experiences are conditioning factors of political activism. However, the mechanisms through which this effect occurs are still poorly understood. Aiming to advance this topic, this article presents the results of an investigation that looked to analyse the mediated effects of personality traits in the Brazilian context, taking as mediating conditioning factors various attitudes and subjective dispositions commonly found in the literature, such as interest in politics and subjective political efficacy. Using the Latin American Public Opinion Project data, the hypothesis was tested that personality influences behaviour, since it favours the development of a number of attitudes that function as basic factors conditioning civic engagement. The results indicate the significant mediated effects of extroversion and openness to experience, especially with regard to political knowledge. This relative disinterest can be partially explained by the difficulty involved in defining what personality is and by the absence of a basic taxonomy that could be used in empirical studies for the purpose of generating reliable data .Nonetheless, this scenario has altered significantly over the last decade and such obstacles have begun to erode with the development of instruments capable of capturing these psychological structures in a sufficiently succinct form to be included in conventional questionnaires. The immediate effect of these advances has been the recent publications of a number of studies venturing into the terrain of relations between participatory political behaviour and personality (DENNY and DOYLE,