Language processing is an extremely important, uniquely human cognitive ability. For well over a century, researchers have sought to understand how the human brain implements a system for instantaneously recognizing and generating complex linguistic patterns. Left perisylvian regions are considered to have certain computational abilities that are essential for "core" language processes, and that are lacking in other brain regions. When left perisylvian regions are damaged in adulthood, language abilities will almost certainly be impaired with limited potential for recovery. However, language processing is more bilateral in young children, and left-lateralization strengthens over the first decade of life. Moreover, when left perisylvian regions are damaged at the beginning of life, language is not chronically impaired as it is after a similar injury in adulthood: right perisylvian regions are able to support a language system in these individuals. The current dissertation uses data collected previously to examine the cortical organization of language processing to evaluate which features may or may not be essential for a fully intact language system. In the first study, we investigated whether the right hemisphere areas that were active for language processing early in life still exhibit a weak but spatially intact response during language processing in the mature brain. The final two studies used data from the Pediatric Stroke Research Project, a comprehensive study of language and other cognitive abilities in participants with perinatal strokes as well as in their healthy siblings. Left hemisphere perinatal stroke is an important model of developmental flexibility in language network organization because the injury occurs close to birth and often has no other significant health consequences. In the second and third studies, we investigated how the language system becomes mapped in an alternative functional layout in the right hemisphere of left hemisphere perinatal stroke participants, and how this mapping allows for two important cognitive functions--ordinarily in different hemispheres--in this case to develop in one hemisphere, in the only complete set of perisylvian regions available. Collectively, these findings have important implications for the principles of development of functional localization, and plasticity in higher cognitive functions after cortical injury. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]