This chapter investigates whether sentence comprehension difficulty in aphasia can be explained in terms of retrieval processes. By modelling individuals with aphasia (IWAs) separately, we show that different IWAs show impairments along different dimensions: slowed processing, intermittent deficiency, and resource reduction. The parameters in the cue-based retrieval model have a theoretical interpretation that allows these three theories to be implemented within the architecture. In a further investigation, we compare the relative predictive accuracy of the cue-based model with that of the direct-access model. The benchmark data here are from Caplan et al. (2015); k-fold cross-validation is used as in the preceding chapter. The cue-based retrieval model is shown to have a better predictive performance.