  We develop a general framework, based on Boltzmann transport theory, to
analyze the distribution of wealth in societies. Within this framework we
derive the distribution function of wealth by using a two-party trading model
for the poor people while for the rich people a new model is proposed where
interaction with wealthy entities (huge reservoir) is relevant. At equilibrium,
the interaction with wealthy entities gives a power-law (Pareto-like) behavior
in the wealth distribution while the two-party interaction gives a
Boltzmann-Gibbs distribution.
