Economic forces, policy initiatives, and technological change push mar
kets along what some hypothesize is a common evolutionary path. Observ
ations from twelve sites, however, indicate that the pace and directio
n of change are highly variable across markets. Other forces, internal
and unique to a community, help to explain this variation. These forc
es emanate from the underlying history, culture, and values of a commu
nity and in part dictate the response of various players to the more c
ommon forces, This paper explores the mechanisms through which these f
orces operate and their relationship to health system change.