Pentecostalism is a religious movement, spreading, from its origins in the early twentieth century and more strongly since the 1950s, to the entire Latin American continent, mainly through ethnic and class segments located in the lower parts of the social pyramid. With the pass of the time, Pentecostalism showed a great capacity for theological and organisational recreation, but did not cut, despite this, its basic ties with evangelical heritage. This dynamism has strengthened its public presence from the religious point of view while its civic impact is still in great part unknown, and led to various hypotheses that present this movement as associable to democracy and, conversely, as opposed to its founding values and to the change of social structures in a 'progresist' sense. It is clear however that the Pentecostals have been the excuse to debate the issue of 'invasion of the sects ' by those who stigmatised its churches, especially in the 80's. This paper works these aspects and presents methodological demands that seem appropriate to take into account in friture compara-tive studies in Latin American countries. [ABSTRACT FROM AUTHOR]