A broad range of state-of-the-art molecular beam methods to determine dielectric of clusters are presented. The experimental setup and underlying physical concepts of these experiments are described. Furthermore, existing theoretical models to explain the experimental observations are introduced and the possibility to deduce structural information from measurements of dielectric properties is discussed. Additional case studies are presented in the book to emphasize the possibilities but also drawbacks of the methods. Furthermore, two newly developed experimental tools are described which allow to experimentally determine dynamic polarizabilities and to manipulate the motion of neutral species using their known dielectric properties.