  The desirability of evaluating the effective potential in field theories near
a phase transition has been recognized in a number of different areas. We show
that recent Monte Carlo simulations for the probability distribution for the
order parameter in an equilibrium Ising system, when combined with low-order
renormalization group results for an ordinary $\phi^4$ system, can be used to
extract the effective potential. All scaling features are included in the
process.
