  In a previous paper ([1]), we associated a holonomy groupoid and a C*-algebra
to any singular foliation (M,F). Using these, we construct the associated
pseudodifferential calculus. This calculus gives meaning to a Laplace operator
of any singular foliation F on a compact manifold M, and we show that it can be
naturally understood as a positive, unbounded, self-adjoint operator on L2(M).
