This article provides an overview of natural phonological processes in the dialect of Sistani Persian spoken in Iranian Sistan, and reviews theoretical implications of these processes. A representative selection of processes in the language is examined in reference to conditioning by surrounding segments and conditioning in reference to syllable structure. While assimilation and dissimilation are tied to segmental context, deletion, epenthesis and metathesis are considered in light of syllable structure requirements. Synchronically, natural processes include those that are of an allophonic nature as well as those which involve morphophonological alternation. The description of these phenomena is corroborated by a discussion of the application of natural processes in diachronic changes. The authors show that, in some cases, the Sonority Sequencing Principle (SSP) is violated in Sistani Persian. This phenomenon is attributed not to language-internal factors, but rather to the generalization of marked structures as a result of interference from Standard Persian.
