  We apply extensive Monte Carlo simulations to study the probability
distribution $P(m)$ of the order parameter $m$ for the simple cubic Ising model
with periodic boundary condition at the transition point. Sampling is performed
with the Wolff cluster flipping algorithm, and histogram reweighting together
with finite-size scaling analyses are then used to extract a precise functional
form for the probability distribution of the magnetization, $P(m)$, in the
thermodynamic limit. This form should serve as a benchmark for other models in
the three-dimensional Ising Universality class.
