  It is shown, that the Boltzmann-like equations allow the formulation of a
very general model for behavioral changes. This model takes into account
spontaneous (or externally induced) behavioral changes and behavioral changes
by pair interactions. As most important social pair interactions imitative and
avoidance processes are distinguished. The resulting model turns out to include
as special cases many theoretical concepts of the social sciences.
  A Kramers-Moyal expansion of the Boltzmann-like equations leads to the
Boltzmann-Fokker-Planck equations, which allows the introduction of ``social
forces'' and ``social fields''. A social field reflects the influence of the
public opinion, social norms and trends on behaviorial changes. It is not only
given by external factors (the environment) but also by the interactions of the
individuals. Variations of the individual behavior are taken into account by
diffusion coefficients.
