The Medicare Participating Physician Program was enacted in 1984 in an effort to increase physician assignment of Medicare claims, and thereby reduce beneficiary out of-pocket expenses. The program offers the physician the security of near-certain payment on all claims, although at rates that are in many cases, at levels substantially, less than actual physician fees. This paper examines the economic factors that influence the physician's decision on participation. Physicians of the Medical Society of Prince William County, Virginia, were surveyed for information relevant to making the participation decision and the responses tabulated and used as input to a regression equation estimated using the logit technique. Physicians are more likely to participate the higher the relative price received for participating and the lower the probability of payment by Medicare-eligible patients. Additionally, salaried physicians are more likely to partiCipate than those who are self-employed. / Master of Arts