The paper analyses the Lebanese political system called Lebanese consociationalism (confessionalism) focusing on its dynamics and reaction to social changes, particularly demographic. Scholarly literature defines the system as a power-sharing model, a set of political tools implemented to contain challenges arising from ethno-religious pluralism of a society. Important section of the theory is dedicated to conditions that impact dynamics of these systems and decide about its reaction towards challenges, in consequence impacting their stability, durability and success. The following paper joins discussion about Lebanese confessionalism and its reaction towards challenges, especially those posed by changing demographic composition. The paper refers first to the case of the Armenian community in Lebanon and their successful integration into the system also labelled as „lebanonization” as a significant example of the system’s dynamics. As contrasting case the paper also recalls the case of total systemic rejection and marginalization of a community – the Palestinians who came to Lebanon after 1948. The aim is to point at the conditions influencing the system’s divergent responses and operation in the context of dealing with the new communities.