Cognitive rehabilitation for people with acquired brain injury first became a clinical focus in the late 1970s. This chapter addresses cognition from a particular vantage point largely informed by psychological, psycholinguistic, and cognitive research. Cognitive skills and processes are discussed and rehabilitative avenues reviewed insofar as they are the focus of concern for persons with acquired brain injury. The information presented herein provides detailed insight into a particular approach to cognitive rehabilitation that has been used for over three decades and has been found to be effective in restoration of improved cognitive function following brain injury. Attention is foundational to cognition overall. Sensory information entering the central nervous system (CNS) makes its way to the brain stem with the exception of visual and olfactory stimuli. The human perceptual system is inherently designed to give priority to certain types of perceptual cues. Classification or categorization allows for large amounts of information to be managed.