Recent research on silicon grain boundaries has confirmed the typical features known from earlier work on grain boundaries in germanium and III‐V compound semiconductors. However, there is less clarity with respect to the role of the ‘‘dangling bonds’’ when testing for electrical activity. In silicon a pronounced double barrier with its space‐charge layer and a low leakage current rarely forms. Here the Cottrell atmospheres in conjunction with impurity complexes such as SiO, SiO2, and SiO4can strongly influence the electrical properties in a material with an exceptionally high self‐diffusivity. Conditions for the measurability of the longitudinal impurity band‐type conduction through space‐charge layers in silicon grain boundaries are outlined. It is concluded that in those cases where electrical activity is measured, the conduction parallel to the grain‐boundary plane should be apparent for pure material and at low temperature. Experiments are proposed to further our understanding of the properties of grain boundaries in silicon.