The kinetic theory of gases, founded by Maxwell and Boltzmann in the second half of XIXth century, is a statistical theory describing the motion of a very large number of gas molecules in the phase space of one single point particle - i.e. the set of positions and velocities of that particle. However, some very natural problems in kinetic theory require using a larger phase space,including some additional variables describing the correlations of the typical moving particle with its environment. The talk will discuss two examples of this situation.