Analyses of 55 core samples from moderate to low-permeability sandstones in the Travis Peak Formation and underlying Cotton Valley Group in eastern Texas have been performed at IGT. Results of these analyses, as well as earlier work at IGT, demonstrate that tight gas sandstone is a distinct petrologic type, where unique correlations have been found between features of the pore geometry and matrix flow properties. Recognition and quantification of this relationship has led to an improved understanding of the nature of two-phase (gas water) fluid flow through these rocks. Relative permeability and critical gas saturation measurements on these samples revealed the need for improved laboratory techniques for handling tight rocks. Confining stress cycling and the method of establishing partial water saturations were found to be particularly important.