Ab initio calculations were carried out For critical point regions of the acetylene dimer potential surface with different basis sets, with and without the inclusion of counterpoise correction, and at two different electron correlation levels. The results were used to determine parameters For model interaction potentials with different forms for their electrostatic terms, Vibrational quantum Monte Carlo calculations for rigid monomers were performed using each of the model potentials, and refinements of the few parameters in the model potentials were obtained, such that the calculated rotational constant for the ground vibrational state matched the experimentally determined value. Comparison of features of the resulting surfaces showed that similar surfaces could be obtained from the different ab initio starting points, an indication of the suitability of the potentials forms and of the nature of lingering errors in the: ab initio treatments. This provides a very useful basis for more general model development. Specific information obtained about the acetylene dimer is that the changes in the rotational constant due to vibrational averaging are about 2% and that the dissociation energy from the ground vibrational state is about 400 cm(-1).