In the present paper we propose that in Modern Greek a sub-group of discourse particles demonstrates a double function. Specifically, we propose that these discourse particles may function both as signals related to the structure of the discourse and as indicators of positive politeness, which is characteristic of Modern Greek (Sifianou (2001)). Thus, this subgroup of discourse particles, which we will name “politeness markers” also constitutes a cultural element in Modern Greek dialogs. In contrast to the “politeness markers”, we additionally observe that another subgroup of discourse particles, referred to as “non-politeness markers”, function as signals indicating lack of positive politeness and pleasant attitude in Modern Greek dialogs.The behavior of discourse particles was evaluated for the construction of a dialog system for Speech Technology applications in the domain of customer service.