%0 Journal Article %T The Muhly-Renault-Williams theorem for Lie groupoids and its classical counterpart %A N. P. Landsman %J Physics %D 2000 %I arXiv %X A theorem of Muhly-Renault-Williams states that if two locally compact groupoids with Haar system are Morita equivalent, then their associated convolution C*-algebras are strongly Morita equivalent. We give a new proof of this theorem for Lie groupoids. Subsequently, we prove a counterpart of this theorem in Poisson geometry: If two Morita equivalent Lie groupoids are s-connected and s-simply connected, then their associated Poisson manifolds (viz. the dual bundles to their Lie algebroids) are Morita equivalent in the sense of P. Xu. %U http://arxiv.org/abs/math-ph/0008005v1