The Chilcott-Rallison FENE dumbbell model is used to solve for the polymer and flowfield response in transient startup flow of a dilute solution in a corotating two-roll mill. These predictions are then compared to experimental results obtained in an identical geometry using a high molecular weight dilute (c/c* similar to 0.1) polystyrene solution. As predicted by the dumbbell model, the experiments indicate a substantial coupling between the polymer deformation and changes to the Newtonian flowfield. As the polymer stretches, the experimentally measured shear rate decreases as does the Bow-type parameter. However, dumbbell model parameters based upon an isolated chain do not result in FENE model predictions quantitatively similar to the experimental results. Based upon steady-state birefringence values for the same dilute solution in an extension dominated Bow at large strain rates, it appears that chain-chain interactions restrict the maximum attainable polymer deformation. Further calculations incorporating this concept, via a reduced value of the extensibility parameter L, result in much better agreement with experimental results.