Electronic Journal of Differential Equations, Vol. 1999(1999), No. 38, pp. 1-20. Title: Boundary behavior and estimates for solutions of equations containing the $p$-laplacian Authors: Jacqueline Fleckinger (Univ. Toulouse-1, Toulouse, France) Evans M. Harrell II (Georgia Tech, Atlanta, GA, USA) Francois de Thelin (Univ. Paul Sabatier, Toulouse, France) Abstract: We use ``Hardy-type'' inequalities to derive $L^q$ estimates for solutions of equations containing the $p$-Laplacian with $p>1$. We begin by deriving some inequalities using elementary ideas from an early article [B3] which has been largely overlooked. Then we derive $L^q$ estimates of the boundary behavior of test functions of finite energy, and consequently of principal (positive) eigenfunctions of functionals containing the $p$-Laplacian. The estimates contain exponents known to be sharp when $p=2$. These lead to estimates of the effect of boundary perturbation on the fundamental eigenvalue. Finally, we present global $L^q$ estimates of solutions of the Cauchy problem for some initial-value problems containing the $p$-Laplacian. Submitted July 13, 1999. Published September 28, 1999. Math Subject Classifications: 35J60, 35J70. Key Words: p-Laplacian; Hardy inequlity;principal eigenvalue; boundary estimate; boundary perturbation.