VR offers the potential to develop human testing and training environments that allow for the precise control of complex stimulus presentations in which human cognitive and functional performance can be accurately assessed and rehabilitated. However, basic feasibility issues need to be addressed in order for this technology to be reasonably and efficiently applied to the neuropsychological assessment (NA) and cognitive rehabilitation (CR) of persons with acquired brain injury and neurological disorders. This chapter will provide an introduction to the basic concepts of neuropsychological assessment and cognitive rehabilitation along with rationales for virtual reality's applicability in these complimentary fields. We review the relevant literature regarding theoretical and pragmatic issues for these applications, and provide a description of our ongoing work developing a mental rotation/spatial skills cognitive assessment and training system. References are provided in each section for further reading in each area reviewed.