Summary: This study considers the institutional construction of the Order of Friars Minor and the political influence of its model of governance on medieval civil societies. Initially the Order itself was preponderantly influenced by the cistercian model (especially with regard to its Chapters), recommended by the Papacy starting with the Fourth Lateran Council of 1215. Then, beginning in 1239, following the autocratic rule of Brother Elias, and under the guidance of Minister General Haymo of faversham, the frame of reference changed to the more "democratic" one of the Order of Preachers. There is evidence in the chronicles, in theConstitutions of 1239, in the commentaries on the Rule, of a collective choice of a pyramid-like-structure, which derives its legitimacy from the charismatic power of Francis of Assisi, and at the same time form its being built on a base that comprises all the Friars. The changes introduced with Bonaventure of Bagnoregio at the head of the Order, codified in the 1260 Narbonne Constitutions, maintain the same democratic and "parlamentary" appearence, even as they armour-plate the system to favour an èlite of superiors (the more learned Friars and clerics), who constitute themselves into a fairly closed caste. After 1260, the institutional system develops further, no longer through sudden changes but rather by way of  "stratification" (J. Dalarun). This "stratification" brings about, in effect, a system of "checks and balances" where each stratum is corrected, "checked and balanced-out" by the next one, without the aggregate of them being absorbed completely by a not always peaceful synthesis of "democracy" with the "presidentialism" of the Minister General (a kind of "democratic centralism", one might say). Thanks to their "international" expansion, the Friars Minor then aid in the spreading of their manner of governance in mediaeval civil society. It is an undeniable fact thet there were "political" relations (P. Evangelisti) between the Franciscans and the civil governing institutions, both monarchical ones (especially in the Iberian Peninsula) and those of the Communes (above all, in Italy), into which the Friars Minor "infused", in a kind of reciprocal osmosis, something of their conception and practices of governance. This is the case even while it is not possible to estabilish that there was any institutional influence in any strict sense, in either direction.