In this paper I examine the function and the use of un poco and of its morphological alterations (un poquito, un poquitín, etc.) in different levels: in speech acts, in propositions, in speech, in social relationship established between speaker and hearer, and, finally, in context. Theoretical framework of the analysis is, primarily, modality, a notion applying to utterances and indicating the compromise level which the speaker maintains in respect of the utterance faithful. Secondly, I refer to mitigation within the most general theory of Politeness, in which this is a strategy to modulate speech act effects (Lakoff, 1972; Caffi, 1999, 2002, 2007). Here I examine the function of un poco from a semantic-pragmatic perspective also taking into account discourse's dimensión and the situations in which they occur. To study the phenomenon, I use real conversations' data proceeding by the Corpus de Conversaciones Coloquiales Val.Es.Co and by the Corpus de Referencia del Español Actual CREA, to which I add some fragments proceeding by conversations that I recorded and transcribed. [ABSTRACT FROM AUTHOR]