Ion-radical reactions require special methods to stimulate or impede them. The speci city of these methods is determined with particular properties of ion-radicals. Many ion-radical syntheses are highly selective yielding products unattainable by other methods. The aim of this chapter is to analyze the phenomena that determine the ways to optimize ion-radical reactions. This chapter considers factors governing the development of the reactions with proven ion-radical mechanisms. Two groups of optimizing factors will be discussed: physical and purely chemical ones. Factors such as solvent change and salt addition are certainly in the borderline between chemical and physical effects.