This article examines the information technology functions, staffing and co
st, services provided, and advanced technologies among health maintenance o
rganizations (HMOs) using a national sample of HMOs from mid-1995. HMOs hav
e a well-developed capability to use data from administrative functions, su
ch as claims processing. Nationally affiliated HMOs and HMOs in markets wit
h greater Hh HMO penetration support more IT functions. Relatively little w
ork has been completed integrating clinical with administrative systems.