Many processes contribute to the speech production system. Brain damage can lead to a wide variety of disorders of the spontaneous production of sentences. Different symptoms of a sentence construction disorder, such as agrammatic and paragrammatic speech errors, are briefly described. An explicit model of the grammatical processes is proposed, and it is shown how the symptoms can be explained in terms of selective impairments to components of the model. The construction of subject-verb agreement in speech is treated in detail.