First Day of a New Congress: A Guide to Proceedings on the House Floor [July 24, 2017] [open pdf - 631KB]
"The House of Representatives follows a well-established routine on the opening day of a new Congress. The proceedings include electing and swearing in the Speaker, swearing in Members, electing and swearing in House administrative officers, and adopting rules of procedure and various administrative resolutions. Resolutions assigning some or many Members to committees may also be adopted. The House must take these actions at the beginning of each new Congress because it is not a continuing body. Article 1, Section 2 of the Constitution sets a term of office for Members of the House at two years. Thus, one House ends at the conclusion of each two-year Congress, and the newly elected Representatives must constitute a new House at the beginning of a new Congress."
CRS Report for Congress, RL30725
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html