2005–06 Swiss 1. Liga

The '''2005–06 Swiss 1. Liga''' was the 74th season of this league and was, at this time, the third tier of the Swiss football league system. The 1. Liga was the highest level of amateur football, although an ever-increasing number of teams had professional or semi-professional players in their ranks, this also included the U-21 teams, the eldest youth teams of the professional clubs.

Format
There were 48 teams in this division this season, including eight 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 groups winners and three 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 the play-offs. The two last placed teams in each group were relegated to the 2. Liga Interregional.

Group 1
Last season's group winners Lausanne-Sport had achieved promotion to the second tier. Further, ES FC Malley and Stade Lausanne Ouchy had been relegated and were no longer represented in this division. New clubs in this season were Signal FC Bernex-Confignon and SC Düdingen who had both been promoted after winning their 2. Liga Interregional groups. FC Bulle joined the group after being relegated following the 2004–05 Challenge League season. Also new to the group was Servette. During February 2005, the parent company of the club was declared bankrupt and as a consequence their U-21 team took over the club name playing two divisions below the original Servette team.

Group 2
Last season's bottom two clubs FC Alle and FC Langenthal had suffered relegation. They were replaced by FC Kickers Luzern and SV Muttenz who had both been promoted after winning their 2. Liga Interregional groups respectively. FC Laufen were also promoted after being the best second placed team. Last season's group champions FC Biel-Bienne had missed promotion and remained in the group.

Group 3
Last season's bottom two clubs FC Chur 97 and FC Gossau had suffered relegation. Last season's group winners FC Tuggen had missed promotion and remained in the group. However runner's-up Locarno had achieved promotion, winning the play-offs. Theses teams were replaced by FC Rapperswil-Jona who had been promoted after winning the 2. Liga Interregional group 5 the previous season. Further new to this group were SC Cham and Zug 94 who had played the previous season in group two.

Qualification round
 Servette win 6–1 on aggregate

 Delémont win 7–0 on aggregate

 Étoile Carouge win 4–2 on aggregate

3–3 on aggregate UGS win on away goals

Final round
 Delémont win 2–1 on aggregate and are promoted to the 2006–07 Challenge League.

 Servette win 5–1 on aggregate and are promoted to the 2006–07 Challenge League.

Summary
Group 1 champions were Servette, who also achieved promotion in the play-off finals. Runners-up in this group were UGS, who missed their promotion attempt, being defeated by Servette in this play-off final. Group 2 champions were Biel-Bienne and runners-up were Delémont, who had been relegated two season before. Biel-Bienne failed in their promotion attempt, but Delémont achieved promotion winning against group 1 third placed team Étoile Carouge in the finals. In group 3 champions Tuggen, runners-up Red Star and third placed Herisau all failed in the play-off qualification. From group 1 Signal FC Bernex-Confignon and Grand-Lancy FC were relegated. From group 2 FC Schötz and SC Buochs and from group 3 FC Altstetten and FC Frauenfeld also suffered the same fate and continued the next season in the 2. Liga Interregional.

The remaining teams in the 1. Liga were to be joined in next season by Sion U-21, FC La Tour/Le Pâquier, FC Mendrisio-Stabio, FC Olten and FC Gossau, all of whom had won their 2. Liga Interregional groups. Winterthur U-21 as best second placed team also achieved promotion.