The term “social polarization” is used to describe a society that is composed of different socially identifiable and separate groups. Social polarization is a key feature of many modern societies and is potentially linked to conflicts, alienation, and societal tensions. When concerning income, polarization (or, more precisely, bipolarization) describes the so‐called disappearance‐of‐the‐middle‐class phenomenon, that is, the tendency of the income distribution to become U‐shaped, with the population shifting toward the two extremes of the income range, emptying the central part of it. Polarization is a different concept from inequality and requires different indexes to be measured. Many formulas exist in the statistical literature, both for univariate cardinal and ordinal variables, but there still lacks a satisfactory measurement theory for multidimensional polarization.