Surface chemical effects on colloidal stability and transport through porous media were investigated using laboratory column techniques. Approximately 100nm diameter, spherical, iron oxide particles were synthesized as the mobile colloidal phase. The column packing material was retrieved from sand and gravel aquifer on Cape Cod, MA. Previous studies have indicated enhanced stability and transport of iron oxide particles due to specific adsorption of some inorganic anions on the iron oxide surface. This phenomenon was further evaluated with an anionic surfactant, sodium dodecyl sulfate. Surfactants constitute a significant mass of the contaminant loading at the Cape Cod site and their presence may contribute to colloidal transport as a significant transport mechanism at the site. Photon correlation spectroscopy, micro-electrophoretic mobility, and scanning electron microscopy were used to evaluate particle stability, mobility, and size. Adsorption of negatively charged organic and inorganic species onto the surface of the iron oxide particles was shown to significantly enhance particle stability and transport through alterations of the electrokinetic properties of the particle surface. Particle breakthrough was primarily dependent upon colloidal stability and surface charge.