This thesis addresses the modeling of the dissolution of residually-trapped multi-component non-aqueous phase liquids (NAPLs) from a porous medium. As part of this work, a model was constructed in which the mass transfer behavior of the NAPL is characterized by a probability density function (pdf) which describes the initial distribution of residual NAPL "blob" volumes. Mass transfer from these trapped NAPL "spheres" is simulated using an empirical relationship for the Sherwood Number, a linear concentration driving force, and multi-component solubility effects. This "Distributed-Site" model is then used to match two sets of dissolution data from a laboratory column test.