| Competition: | 1. Liga |
| Season: | 2004–05 |
| Winners: | Group 1: Lausanne-Sport Group 2: Biel-Bienne Group 3: Tuggen |
| Promoted: | Locarno Lausanne-Sport |
| Relegated: | Group 1: Malley Stade Lausanne Ouchy Group 2: Alle Langenthal Group 3: Chur Gossau |
| Matches: | 3 times 240 plus 12 play-offs |
| Prevseason: | 2003–04 |
| Nextseason: | 2005–06 |
The 2004–05 Swiss 1. Liga was the 73rd season of this league since its creation in 1931 and, at this time, it was the third tier of the Swiss football league system. The 1. Liga was also the highest level of Swiss amateur football, despite an ever-increasing number of clubs in this league playing with professional or, more often than not, semi-professional players in their ranks and this was not just the case with the U-21 teams of the professional clubs.
There were 48 teams in this division, including seven U-21 teams, which were the eldest youth teams of the professional clubs in the Super League and the Challenge League. The 1. Liga was divided into three regional groups, each with 16 teams. Within each group, the teams would play a double round-robin to decide their positions in the league. The three group winners, the runners-up, together with the two best third placed teams, then contested a play-off for the two promotion slots. The U-21 teams were not eligible for promotion and could not compete in the play-offs. The two last placed teams in each group were to be directly relegated to the 2. Liga Interregional.
| Club | Canton | Stadium | Capacity |
|---|---|---|---|
| FC Bex | Vaud | Relais | |
| CS Chênois | Geneva | Stade des Trois-Chêne | |
| FC Echallens | Vaud | Sportplatz 3 Sapins | |
| Étoile Carouge FC | Geneva | Stade de la Fontenette | |
| FC Fribourg | Fribourg | Stade Universitaire | |
| Grand-Lancy FC | Geneva | Stade de Marignac | |
| Lausanne-Sport | Vaud | Stade Olympique de la Pontaise | |
| ES FC Malley | Vaud | Centre Sportif de la Tuilière | |
| FC Martigny-Sports | Valais | Stade d'Octodure | |
| FC Naters | Valais | Sportanlage Stapfen | |
| FC Serrières | Neuchâtel | Pierre-à-Bot | |
| Servette U-21 | Geneva | Stade de Genève | |
| FC Stade Lausanne Ouchy | Vaud | Centre sportif de Vidy | |
| FC Stade Nyonnais | Vaud | Stade de Colovray | |
| Urania Genève Sport | Geneva | Stade de Frontenex | |
| Young Boys U-21 | Bern | Stadion Neufeld or Allmend Bern | |
| Club | Canton | Stadium | Capacity |
|---|---|---|---|
| FC Alle | Jura | Centre Sportif Régional | |
| Basel U-21 | Basel-City | Stadion Rankhof or Leichtathletik-Stadion St. Jakob | |
| FC Biel-Bienne | Bern | Stadion Gurzelen | |
| SC Buochs | Nidwalden | Stadion Seefeld | |
| SC Cham | Zug | Stadion Eizmoos | |
| SR Delémont | Jura | La Blancherie | |
| SC Dornach | Solothurn | Gigersloch | |
| FC Grenchen | Solothurn | Stadium Brühl | |
| FC Langenthal[1] | Rankmatte | ||
| Luzern U-21 | Lucerne | Stadion Allmend or Allmend Süd | |
| FC Münsingen | Bern | Sportanlage Sandreutenen | |
| FC Schötz | Lucerne | Sportplatz Wissenhusen | |
| FC Solothurn | Solothurn | Stadion FC Solothurn | |
| FC Wangen bei Olten | Solothurn | Sportplatz Chrüzmatt | |
| SC Zofingen | Aargau | Sportanlagen Trinermatten | |
| Zug 94 | Zug | Herti Allmend Stadion | |
| Club | Canton | Stadium | Capacity |
|---|---|---|---|
| FC Altstetten[2] | Zürich | Buchlern | |
| GC Biaschesi | Ticino | Campo Sportivo "Al Vallone" | |
| FC Brugg | Aargau | Stadion Au | |
| FC Chur 97 | Grisons | Ringstrasse | |
| FC Frauenfeld | Thurgau | Kleine Allmend | |
| FC Gossau | St. Gallen | Sportanlage Buechenwald | |
| Grasshopper Club U-21 | Zürich | GC/Campus Niederhasli | |
| FC Herisau | Appenzell Ausserrhoden | Ebnet | |
| FC Kreuzlingen | Thurgau | Sportplatz Hafenareal | |
| FC Locarno | Locarno, Ticino | ||
| FC Mendrisio | Ticino | Centro Sportivo Comunale | |
| FC Red Star Zürich | Zürich | Allmend Brunau | |
| FC Seefeld Zürich[3] | Zürich | Sportanlage Lengg | |
| St. Gallen U-21 | St. Gallen | Espenmoos | |
| FC Tuggen | Schwyz | Linthstrasse | |
| Zürich U-21 | Zürich | Sportplatz Heerenschürli | |
Qualified for the play-offs were the first two teams from group 1; Lausanne-Sport and Serrières, from group 2; Biel-Bienne and Wangen b.O. and from group 3; Tuggen and Locarno. The two best third best teams were Étoile Carouge from group 1 and Red Star from group 3.
Étoile Carouge win 3–1 on aggregate and advance to Finals. Lausanne-Sport win 8–3 on aggregate and advance to Finals. Locarno win 2–1 on aggregate and advance to Finals. Red Star win 6–2 on aggregate and advance to Finals.
Locarno win 4–1 on aggregate and are promoted to 2005–06 Challenge League. Lausanne-Sport win 5–4 on aggregate and are promoted to 2005–06 Challenge League.
Group 1 champions were newly promoted Lausanne-Sport, they also achieved immediate promotion to the 2005–06 Challenge League. Runners-up in this group were Serrières, but they failed in their promotion attempt. Group 2 champions were Biel-Bienne and runners-up were Wangen b.O.. However, both failed in their promotion attempts. The champions of group 3, Tuggen, also missed promotion. The runners-up in group 3 were Locarno and they achieved promotion. Relegated were Malley and Stade Lausanne Ouchy from group 1, Alle and Langenthal from group 2 and from group 3 Chur and Gossau. The remaining teams in the division were to be joined in next season by Signal FC Bernex-Confignon, SC Düdingen, FC Kickers Luzern, SV Muttenz and FC Rapperswil-Jona, all of whom had won their 2. Liga Interregional groups.[4]