Electronic Journal of Differential Equations, Vol. 2004(2004), No. 44, pp. 1-12. Title: Boundary monotonicity formulae and applications to free boundary problems I: The elliptic case Author: Georg S. Weiss (Univ. of Tokyo, Japan) Abstract: We derive a monotonicity formula at boundary points for a class of nonlinear elliptic partial differential equations, including the obstacle problem case, quenching, a free boundary problem with Bernoulli-type free boundary condition as well as the blow-up case. As application model we prove - for Dirichlet boundary data satisfying certain assumptions - the global existence of a classical solution of the free boundary problem with Bernoulli-type free boundary condition in two and three dimensions. Submitted October 13, 2003. Published March 29, 2004. Math Subject Classifications: 35R35, 35J67, 35J60. Key Words: Free boundary; boundary regularity; non-tangential touch; monotonicity formula; global regularity; Bernoulli-type free boundary condition.