  We derive, through analysis of the structure of diagrammatic perturbation
theory, the scaling behavior of the condensate and superfluid mass density of a
dilute Bose gas just below the condensation transition. Sufficiently below the
critical temperature, $T_c$, the system is governed by the mean field
(Bogoliubov) description of the particle excitations. Close to $T_c$, however,
mean field breaks down and the system undergoes a second order phase
transition, rather than the first order transition predicted in Bogoliubov
theory. Both condensation and superfluidity occur at the same critical
temperature, $T_c$ and have similar scaling functions below $T_c$, but
different finite size scaling at $T_c$ to leading order in the system size.
Through a simple self-consistent two loop calculation we derive the critical
exponent for the condensate fraction, $2\beta\simeq 0.66$.
