Our concepts about objects, states, and events are stored in a cognitive structure termed semantic memory. There are several types of neurologic disorders that may cause impairments of semantic memory. Clinical evaluations of these impairments are complex, because semantic memory is linked to other cognitive systems that, when damaged, may produce related syndromes or difficulties. In an attempt to gain further understanding of these breakdown patterns, we review data from both neuropsychologic and brain activity research that have been concerned with how object concepts are represented and localized in the brain. Although these data have spawned varying and controversial views regarding the content and organization of semantic knowledge, converging evidence suggests that semantic memory is mainly localized in the posterior region of the left temporal lobe, and that particular categories of knowledge may be represented in different but overlapping regions within this area.