This research is a collaborative effort to recalibrate and extend the widely used MELTS computational thermodynamics software package in order to simulate magmatic processes such as mantle melting, crystal fractionation, and melt-rock reaction to pressures of ~25 GPa. This extension of MELTS will utilize an associated solution approach to the thermodynamics of the liquid phase and will depend on improvements to the scope and the quality of the experimental calibration database. This new database is being constructed from literature data and from new experiments designed (1) to provide calibration ground-truth for critical portions of temperature-pressure-composition space and (2) to resolve conflicts identified in the existing database. The revised MELTS software package and new experimental database will be distributed to the Earth Sciences community at http://melts.uchicago.edu.