The compliance coefficients and Stillinger-Weber interatomic potential parameters of wurtzite InN were determined by first principles methods. The structural parameters of InN were calculated within the local density approximation of Ceperley-Alder and the generalized gradient approximation of Perdew-Wang exchange-correlation functionals. It was found that the shallow 4d electrons were required as part of the valence shell to obtain accurate results due to the large difference in electronegativity between In and N. The calculated compliance parameters were in good agreement with previously reported theoretical values and in fair agreement with the scattered experimental values. The ab initio results were then fitted to Stillinger-Weber potential forms. (C) 2008 American Vacuum Society.