Bose-Einstein condensation, predicted for a gas of non interacting bosons in 1924 by Einstein, has been demonstrated for the first time in 1995 in a dilute gas of rubidium atoms at temperatures below 10(-6) K. In this work, it is shown that Bose-Einstein condensation can be achieved at around 15-20 K in a solid state system by using microcavity polaritons, which are composite bosons of mass ten billion times lighter than that of rubidium atoms. [DOI: 10.2971/jeos.2008.08023]