This paper presents state-of-the-art examples to show that, in a wide variety of cases, the behavior of geosynthetics can be quantified using theoretical analyses. Seven examples are reviewed: geotextile filter retention, geotextile filter clogging, geomembrane stress-strain behavior, geomembrane strain concentrations, geomembrane stress cracking pattern, geomembrane wrinkles, and geosynthetic resistance to differential settlement. The selected examples are such that the important behavioral aspect is not the behavior of the structure in which the geosynthetic is incorporated, but the behavior of the geosynthetic itself. In each case, the phenomenon or problem is described, the theoretical analysis is presented, and the results are discussed. Note: This is only a preliminary version of the final paper which will appear in the post-conference proceedings volume.