Publisher Summary This chapter summarizes the earlier trends and developments while incorporating the current findings on the phenomenon of sentence processing. Extensive research has been carried out from a number of different perspectives and emphasis is laid on a variety of different types of impairments to sentence processing. One of the primary reasons that agrammatism has been viewed as a coherent, homogeneous entity is the existence of a contrasting grammatical disturbance labeled “paragrammatism.” In many ways, prototypical paragrammatism constitutes the mirror image of agrammatism: paragrammatic sentences are produced fluently (sometimes hyperfluently) and contain many grammatical morphemes (inflections and free-standing function words), though these may be used inappropriately. Agrammatic speakers, labor to produce halting and fragmented sentences that contain content words without the support of grammatical morphemes. Special tests are designed for this pattern, which require the patient to understand the syntactic structure of the sentence and the meaning of the words it contains. All these studies lead to a number of interesting conclusions along with the sentence processing disorders, which can render treatment under the right conditions.