the article assesses the average probability of individuals to take part in participatory processes in participatory institutions (pis), based on a set of socio-economic and political characteristics. from an universe of 2,200 individuals from all brazilian states, who have answered the questionnaire applied by vox populi institute, focused on the subject of social participation (a document written in collaboration with the minas gerais federal university - ufmg), characteristics were assessed from individuals that effectively take part in pis. that information was related to a set of socioeconomic and political profile variables. those variables are: nominal family income; schooling; sex; skin color; participation in associative activities; and region of brazil where they live. an analysis of descriptive statistics was conducted among the variables, trying to build statistical models to explain the dependent variable "insertion in participatory institutions' activities" (specifically, municipal management councils, participatory budget, theme conferences), using as a basis four specific theoretical models, namely: the model of centrality, the model of associativism, the model of rational choice, and finally, the institutional model or model of opportunity structures. results indicate that skin color, sex, schooling and previous involvement with associative and political activities play a crucial role in increasing that propensity, but their respective degrees of impact vary according to the participatory institution under consideration.