  Finite-temperature charge-ordering phase transition in quasi one-dimensional
(1D) molecular conductors is investigated theoretically, based on a quasi 1D
extended Hubbard model at quarter filling with interchain Coulomb repulsion
$V_\perp$. The interchain term is treated within mean-field approximation
whereas the 1D fluctuations in the chains are fully taken into account by the
bosonization theory. Three regions are found depending on how the charge
ordered state appears at finite temperature when $V_\perp$ is introduced:
  (i) weak-coupling region where the system transforms from a metal to a charge
ordered insulator with finite transition temperature at a finite critical value
of $V_\perp$,
  (ii) an intermediate region where this transition occurs by infinitesimal
$V_\perp$ due to the stability of inherent 1D fluctuation, and
  (iii) strong-coupling region where the charge ordered state is realized
already in the purely 1D case, of which the transition temperature becomes
finite with infinitesimal $V_\perp$. Analytical formula for the $V_\perp$
dependence of the transition temperature is derived for each region.
