Brain–computer interfacing (BCI) systems involve controlling a computer using brain signals detected by electroencephalography (EEG). Signal processing software uses the EEG signal to control a cursor or application, such as word processing (Birbaumer et al., 1999 and Pfurtscheller et al., 1993). The field of BCI research is at a relatively early stage of producing reliable, robust systems that are widely accessible for everyday use. Several BCI research groups are developing systems to enable communication and environmental control for people with severe disabilities. A more recent area of exploration with BCI is for investigating mechanisms of normal function, dysfunction and recovery, as well as aiding diagnosis and re-training of function. The generation and control of EEG signals for driving a BCI system require training of the user. Methods include imagery tasks, evoked potentials and operant conditioning (for reviews see (Curran and Stokes, 2003 E. Curran and M. Stokes, Brain Cog 51 (2003), pp. 326–335.Curran and Stokes, 2003 and Kubler et al., 2001)). Signal processing techniques continue to be refined (James and Hesse, 2005) and are improving the accuracy and reliability of BCI technology but translation into routine clinical use is limited by several factors influencing accessibility and compliance. Surface or implanted recording devices can be used and for transient use in most areas of rehabilitation, surface electrodes are appropriate. An important aim of BCI research is to bridge the gap between major technological advances and the relatively limited success in practical applications. More clinical disciplines are encouraged to become involved in BCI research to achieve this aim.