Real-time observations of the film stress-thickness product are presented from the growth of strained InGaAs/GaAs layers. Growth temperatures of 440 and 520 degrees C were used with a nominal In composition of x=0.20. The data are compared with a model of relaxation kinetics based on dislocation glide velocity. The residual strain is higher than predicted and the relaxation is not markedly temperature dependent, in contrast to the model. These discrepancies suggest that dislocation blocking causes incomplete relaxation in this material system.