We present a relatively simple technique to constrain in-situ stress and effective rock strength from observations of wellbore failure in inclined wells. Application of this technique in the Global Basins Research Network (GBRN)/DOE "Pathfinder" well demonstrated that (1) the azimuth of S-hmin is approximate to N42 degrees E, perpendicular to a major growth fault penetrated by the well; (2) the magnitude of S-Hmax is relatively close to the vertical stress; and (3) the effective in-situ compressive rock strength is 3,500 to 4,000 psi. We show that once we have estimated in-situ stress and rock strength, it is possible to compute the mud pressure required to inhibit failure for wells of any azimuth and inclination. Finally, we show how it is possible to estimate the magnitudes of both S-hmin and S-Hmax in cases where independent knowledge of stress orientation is available (for example, from wellbore breakouts in nearby vertical boreholes).