The main goal of the present study was to investigate the semantics and processing of three (in)definite markers used in the colloquial Persian. It was proposed that colloquial Persian morphologically realizes two definite markers, the null marker ‘Ø’ and the suffix ‘-e’. It was further proposed that these correspond to so-called “weak” and “strong” definites, respectively; the presuppositions of strong definites need to be satisfied by an explicit antecedent but the presuppositions of weak definites do not. It was also proposed that ‘ye…i’ is an indefinite marker. This proposal was supported by quantitative data from an off-line questionnaire study that measured the naturalness of sentences that only varied in NPs marked with ‘Ø’, ‘-e,’ ‘ye…¬i’ in contexts which (i) an antecedent was available (Given contexts), (ii) an antecedent was unavailable but could be accommodated (Bridged contexts), and (iii) an antecedent was unavailable and accommodation was unlikely (New).