This book explores the nature of the control of language processing by the hemispheres of the neocortex. The author expounds a novel hypothesis, “The Focusing Hypothesis”, which holds that language processing in the brain is achieved through analytic and holistic systems, the former through left and the latter through right hemisphere processing. This hypothesis differs from current thinking in so far as it proposes that the involvement of the two systems (and two hemispheres) depends on the strategy selected by the speaker and that the engagement by one hemisphere over another will depend upon the communicative intent of the speaker and the propositionality of the utterance under production. Throughout the book there are useful and important discussions on such topics as the value of laboratory-based psycholinguistic experiments — given their tendency to encourage a “metalinguistic” strategy on the part of subjects, the nature of propositionality in language and brain and the difficulties of testing this hypothesis given the research approaches currently available. The Focusing Hypothesis is tested by comprehensive review of the existing experimental psycholinguistic, neuropsychological and neurophysiological literature, and a range of predictions which follow from the hypothesis are detailed.