This dissertation deals with intervention effects in non-local dependencies in Persian. The structures taken into analysis include, non-exhaustively, multiple wh-questions, weak-islands and subject-verb agreement.Intervention effects are observed in configurations where an intervener blocks the movement of elements extracted from a hierarchically lower structural position.The theoretical framework on which this dissertation will be based is Chomsky's (1995) Minimal Link Condition (MLC) in terms of AGREE coupled with Relativized Minimality (RM) (Starke 2001, Rizzi 2004). In this dissertation, the role of various features that can modulate the grammatical status of the above-mentioned non-local dependencies is presented and discussed. Some of these features include [+Wh], [+Top(ic)], [+N], [+PP], and [Loc(ative)].In addition, the effects of some of these features on general (real-time) processing of non-local dependencies are discussed thoroughly when relevant.