Comprehension is the aspect of cognition in which information is retrieved and consciously integrated. It occurs between the input of perception and memory, and the output of language and executive functioning. This article focuses on disorders of comprehension of linguistic information and semantic knowledge. Comprehension of speech begins with the interpretation of acoustic-phonetic input as word forms. These concepts to which the word forms are semantically associated must then be retrieved, in parallel with interpretation of word order and grammatical marking, to achieve comprehension of discourse. Neural systems for semantic memory are closely related to those for lexical processing. Disorders of language comprehension and semantic knowledge for concrete entities give insight into the relationship of these processes to neural systems.