The Medicare program incorporates a number of functions that go beyond prov
iding health insurance to its beneficiaries. These activities, which we ref
er to as "collateral" functions, may have important health consequences but
are also an increasing source of controversy. In this essay we develop a c
onceptual framework for categorizing these involvements, introduce some add
itional options that might complement Medicare's current collateral functio
ns, assess the reaction of policy elites and Medicare's current beneficiari
es to these alternatives, and evaluate the role that collateral activities
play for Medicare's core mission. A case can be made for expanding some col
lateral involvements, but only if the Health Care Financing Administration
has the strategic direction and administrative capacity to effectively impl
ement these activities.