The aim of this paper is to present a correct and complete mechanistic picture of nucleophilic substitution in nitroarenes based on the results obtained by theoretical calculations and experimental observations coming from numerous publications, reviews, and monographs. This work gives the theoretical background' to the very well documented experimentally yet still ignOred observations that the addition of nucleophiles to halo nitroarenes resulting in the formation of all adducts, which under proper reaction conditions can be transformed into the product of the SNArH reaction, is faster than the competing process of addition to the carbon atom bearing a riudeofugal group (usually a halogen atom) resulting in the "classic" SNAr reaction. Only when the oil adduct cannot be transformed into the SNAr reaction product, SNAr reaction is observed.