| Club: | Dumbarton |
| Season: | 1920–1921 |
| Manager: | James Collins |
| Stadium: | Boghead Park, Dumbarton |
| League: | Scottish League |
| League Result: | 21st |
| Cup1: | Scottish Cup |
| Cup1 Result: | Fourth round |
| League Topscorer: | Duncan Walker (15) |
| Season Topscorer: | Duncan Walker (21) |
| Highest Attendance: | 10,000 |
| Lowest Attendance: | 2,000 |
| Average Attendance: | 4,000 |
| Pattern B1: | _thin_blackhoops |
| Pattern La1: | _black_hoops |
| Pattern Ra1: | _black_hoops |
| Pattern So1: | _2 gold stripes |
| Leftarm1: | FFD700 |
| Body1: | FFD700 |
| Rightarm1: | FFD700 |
| Shorts1: | FFFFFF |
| Socks1: | 000000 |
| Prevseason: | 1919–20 |
| Nextseason: | 1921–22 |
The 1920–21 season was the 44th Scottish football season in which Dumbarton competed at national level, entering the Scottish Football League and the Scottish Cup. In addition Dumbarton entered the Dumbartonshire Cup and the Dumbartonshire Charity Cup.
See main article: 1920–21 Scottish Football League. Dumbarton witnessed a slump in form finishing in 21st-place out of 22, with 24 points, well behind champions Rangers.[1] In addition to an outflow of some of the team's talent, the inability to score was also a problem, and with just 41 goals to their credit, Dumbarton finishing up as lowest scorers in the league.
The bottom two clubs - Dumbarton and St Mirren - retained their places in the Scottish League. Although the Scottish Second Division had not yet reformed, there was one applicant for promotion - Central League champions, Dunfermline Athletic. However they failed to find a proposer and seconder in the vote.
See main article: 1920–21 Scottish Cup. Dumbarton reached the fourth round before losing out to Rangers.
Dumbarton again failed to progress from the sectional stage of the Dumbartonshire Cup.
Following a draw with Vale of Leven in the semi-final, a replay date could not be arranged and Dumbarton agreed to scratch from the competition.
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Source:[2]
| Player | From | Date | |
|---|---|---|---|
| Peter Brown | Renton | 2 May 1920 | |
| John Browning | Vale of Leven | 2 May 1920 | |
| Thomas Maxwell | Dumbarton Harp | 28 May 1920 | |
| Peter Currie | Clyde | 15 Jun 1920 | |
| Percy Wharrier | Dumbarton Harp | 23 Jun 1920 | |
| George Rae | Dunfermline Athletic | 7 Aug 1920 | |
| Archibald Mackie | Kilmarnock | 14 Aug 1920 | |
| Thomas Mannion | Duntocher Hibs | 8 Sep 1920 | |
| William Fraser | Kirkintilloch Rob Roy | 9 Sep 1920 | |
| Harry Chatton | Kirkintilloch Rob Roy | 22 Sep 1920 | |
| John McTavish | East Fife (loan) | 22 Oct 1920 | |
| Ernest Somerville | Clydebank | 24 Oct 1920 | |
| Eli Cotterill | Chesterton (loan) | 18 Nov 1920 | |
| John McMillan | Duntocher Hibs | 3 Dec 1920 | |
| Arthur Early | Third Lanark | 14 Dec 1920 | |
| Donald Colman | Aberdeen | 28 Dec 1920 | |
| Andrew Chalmers | Girvan | 15 Feb 1921 |
| Player | To | Date | |
|---|---|---|---|
| Alexander Thom | 25 May 1920 | ||
| Alex Bennett | 19 Jul 1920 | ||
| George Rae | Dunfermline Athletic | 23 Oct 1920 | |
| Archibald Mackie | Clydebank | 5 Jan 1921 | |
| Peter Currie | East Stirling | 28 Jan 1921 | |
| Peter Brown | Renton | 29 Jan 1921 | |
| Duncan Walker | St Mirren | 8 Apr 1921 | |
| James Scott | 29 Apr 1921 | ||
| John Duffus | 20 May 1921 | ||
| Scott Duncan | Cowdenbeath (loan) | ||
| Alfred Gettins | Kings Park | ||
| Charles Gordon | Johnstone | ||
| John Hagan | Dumbarton Harp | ||
| James Martin | Bo'ness | ||
| Thomas Maxwell | Dunfermline Athletic | ||
| Bob McGrory | |||
| Patrick O'Connell | Ashington | ||
| John McMillan | Renton | ||
| Patrick O'Connell | Ashington | ||
| John Rowan | Hamilton | ||
| Finlay Speedie | Dumbarton Harp |
Source:[4]