The apportionment of seats in this House of Representatives was based on the 1970 United States census.

Both chambers maintained a Democratic supermajority, and with Jimmy Carter being sworn in as president on January 20, 1977, this gave the Democrats an overall federal government trifecta for the first time since the 90th Congress ending in 1969.

This is the last congress to at any point have no female senators (from its beginning, January 3, 1977, until the swearing-in of Muriel Humphrey (D-MN) on January 25, 1978; and again from the departure of both Humphrey and Maryon Allen (D-AL) on November 7, 1978, to the early swearing-in of Nancy Kassebaum (R-KS) on December 23, 1978).

Members of the House of Representatives elected statewide at-large, are preceded by "At-large", and the names of those elected from districts, are preceded by their district numbers.

The directory after the pages of terms of service lists committees of the Senate, House (Standing with Subcommittees, Select and Special) and Joint and, after that, House/Senate committee assignments.