To develop a medication for the treatment of cocaine addiction using a medical human physio-neuro-psycho-immunology laboratory setting. To characterize this cocaine abusing population on a variety of psychological and physicologically measures over time from withdrawal through pere and post cocaine administration. To determine the effects of selegeline on the subjective and physiological effects of cocaine challenge in chronic crack abusers. To evaluate clinical safety issues pertaining to selegeline, to cocaine and their interaction in a chronic crack dependent population.