The marathon is a specific form of the psycho-process cluster which has its own identifiable characteristics, the basic one being intensity. The primary objective in structuring the marathon is to intensify physical and emotional contact in order to precipitate, encourage, and accelerate the process of behavior change. Myths which have evolved concerning marathons include: (1) participation in a marathon is good for anyone; (2) participation is a quick way to get rid of those "hang-ups" which have plagued you all your life; (3) participation promotes amoral and/or anti-social behavior; and (4) leading a marathon requires little training. Serious professional concerns are being voiced regarding the marathon which need to be dealt with: (1) leadership training; (2) absense of hard data evaluation of the outcomes of the marathon process; (3) publicity or advertisement; and (4) screening of participants. It is time to provide safeguards so that adequate use and protection from misuse can be made of this very effective therapeutic tool. (KJ)