  After a short review of inlationary preheating, we discuss the development of
equilibrium in the frameworks of massless $\lambda \Phi^4$ model. It is shown
that the process is characterised by the appearance of Kolmogorov spectra and
the evolution towards thermal equilibrium follows self-similar dynamics.
Simplified kinetic theory gives values for all characteristic exponents which
are close to what is observed in lattice simulations. This allows estimation of
the resulting reheating temperature.
