The coupling of hydrodynamics to molecular orientation has been studied for a Langmuir film of the hairy-rod polymer poly(p-phenylene)sulfonic acid mixed with either arachidyl alcohol or 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine. These latter materials are small amphiphilic molecules. The orientational dynamics of the polymer under an extensional flow is examined using UV dichroism. The results reveal a surface pressure-induced isotropic-nematic transition, which is affected by polymer-solvent interactions as well as polymer-polymer interactions. An interfacial stress rheometer was used to further examine the existence of the surface pressure-induced transition. These structural and liquid crystalline transitions are difficult to observe using traditional pressure-area isotherm analysis.