This dataset contains a separate record for each officeholder for each United States Congress in which a member has served, with 104 variables describing congressional service and selected biographical characteristics. It includes all the new members of the 99th Congress. There are data for approximately 11,000 individuals in this file, with each person identified by a unique five-digit number. The roughly 39,000 separate records are further identified by the Congress number and chamber/class. Service variables include political party affiliation, district, state and region represented, exact and cumulative dates of service in each Congress and each chamber, as well as total congressional service. Biographical variables include state and region of birth, education, military service, occupation, other political offices held, relatives who have also held congressional office, reason for leaving each Congress, and occupation and political offices held subsequent to service in Congress. Many of these particular variables are summarized in a collapsed variable. Most of the data were derived from merging two existing files--ICPSR's Roster of United States Congressional Officeholders, 1789-1979 and Carroll McKibbin's Biographical Characteristics of Members of the United States Congress, 1789-1978.