| Social Democratic group (S) | |
| Native Name: | German: Sozialdemokratische fraktion French: Groupe socialiste Italian: Gruppo socialista Fracziun Socialdemocratica |
| Chamber: | Swiss National Council and Council of States |
| Foundation: | 1911 |
| Parties: | SP/PS |
| President: | Roger Nordmann |
| Ideology: | Center-left to left-wing |
The Social Democratic Group (abbreviated S) is the second largest parliamentary group in the Swiss Federal Assembly. It is formed by the Social Democratic Party of Switzerland.[1]
The Social Democratic Party were represented in the National Council; they sat as part of the Social-Political group with the democrats from 1896 then formed their own parliamentary group in 1911.[2]
| 22nd (1912) | 17 | 1 | 18 | Gained 1 NC in 1913 then gained 1 NC in 1914 | |
| 23rd (1914) | 19 | 1 | 20 | Lost 1 NC in 1916 then lost 1 NC in 1917 | |
| 24th (1917) | 19 | 1 | 20 | ||
| 25th (1919) | 41 | 0 | 41 | Lost 3 NC then regained 1 NC in 2021 | |
| 26th (1922) | 43 | 1 | 44 | Lost 1 NC then regained 1 NC in 1924 | |
| 27th (1925) | 49 | 2 | 51 | ||
| 28th (1928) | 50 | 0 | 50 | Gained 1 CS in 1930 | |
| 29th (1931) | 49 | 2 | 51 | Lost 1 CS then 1 NC in 1933, then regained 1 NC in 1934 | |
| 30th (1935) | 50 | 3 | 53 | ||
| 31st (1939) | 45 | 3 | 48 | ||
| 32nd (1943) | 56 | 5 | 61 | Lost 2 NC in 1944, gained 1 CS in 1945, then gained 1 NC in 1947 | |
| 33rd (1947) | 48 | 5 | 53 | Lost 1 CS in 1948 then gained and lost 1 CS in 1949 | |
| 34th (1951) | 49 | 4 | 53 | ||
| 35th (1955) | 53 | 5 | 58 | ||
| 36th (1969) | 51 | 2 | 53 | ||
| 37th (1963) | 53 | 3 | 56 | ||
| 38th (1967) | 51 | 2 | 53 | ||
| 39th (1971) | 46 | 4 | 50 | ||
| 40th (1975) | 55 | 5 | 60 | Gained 1 CS in 1978 | |
| 41st (1979) | 51 | 9 | 60 | ||
| 42nd (1983) | 47 | 6 | 53 | ||
| 43rd (1987) | 42 | 5 | 47 | ||
| 44th (1991) | 43 | 3 | 46 | ||
| 45th (1995) | 58 | 5 | 63 | Lost 1 NC in 1999 | |
| 46th (1999) | 53 | 6 | 59 | Lost 1 NC in 2002 | |
| 47th (2003) | 52 | 9 | 61 | ||
| 48th (2007) | 43 | 9 | 52 | Lost 1 NC in 2009, lost 1 NC in 2010, then lost 1 CS in 2011 | |
| 49th (2011) | 46 | 11 | 57 | ||
| 50th (2015) | 43 | 12 | 55 | Lost 1 NC in 2019 | |
| 51st (2019) | 39 | 8 | 47 |
The group is currently presided by national councillor Roger Nordmann (VD)