The in situ electrochemical‐conductance method is presented as an important electrochemical characterization tool for gaining insight into the chemical and electrical behavior of π‐conjugated polymers and electroactive materials. Important information about conductivity models, the type of charge carrier, and the carrier‐transport pathways as well as explanations of different phenomena related to charge and mass transport can be extracted from the obtained analyses. Using conveniently modified polymers, this method enables the development of a wide range of conductometric sensory devices. This Minireview summarizes the historical development of the in situ electrochemical‐conductance method, describes the systems used, explains details of the calculations, and discusses recent advances and applications.