  The Widom-Rowlinson model plays an important role in the statistical
mechanics of second order phase transitions and yet there currently exists no
theoretical approach capable of accurately predicting both the microscopic
structure and phase equilibria. We address this issue using computer
simulation, density functional theory and integral equation theory. A detailed
study of the pair correlation functions obtained from computer simulation
motivates a closure of the Ornstein-Zernike equations which gives a good
description of the pair structure and locates the critical point to an accuracy
of 2 percent.
