This article presents a case study on the political thought and citizenship conceptions of children and adolescents. Considering children and adolescents as reflexive citizens and partners in community development processes, it is our purpose to understand the development of political thought, and particularly how children conceive the exercise of citizenship and participation. Participants were 97 children of a primary and middle secondary (basic) school, aged 5 to 14 years, organized into age groups of 12 children each. Focus group discussions were used as participatory research methodology which involves children as active collaborators, a method that appears to be a good alternative to the traditional individual interviews used in previous research. Results point to the existence of a developmental process of political thought that begins before the start of formal schooling, and a parallel evolution of the conception of social organization and the concepts of citizenship and participation.