| Election Name: | 1938 Dartford by-election |
| Type: | parliamentary |
| Country: | United Kingdom |
| Seats For Election: | Constituency of Dartford |
| Ongoing: | no |
| Previous Election: | 1935 United Kingdom general election |
| Previous Year: | 1935 |
| Next Election: | 1945 United Kingdom general election |
| Next Year: | 1945 |
| Election Date: | 7 November 1938 |
| Candidate1: | Jennie Adamson |
| Party1: | Labour Party (UK) |
| Popular Vote1: | 46,514 |
| Percentage1: | 52.4% |
| Candidate2: | Godfrey Mitchell |
| Party2: | Conservative Party (UK) |
| Popular Vote2: | 42,276 |
| Percentage2: | 47.6% |
| MP | |
| Before Election: | Frank Clarke |
| Before Party: | Conservative Party (UK) |
| After Election: | Jennie Adamson |
| After Party: | Labour Party (UK) |
The 1938 Dartford by-election was held on 7 November 1938. The by-election was held due to the death of the incumbent Conservative MP, Frank Edward Clarke. It was won by the Labour candidate Jennie Adamson. Adamson afterwards stated that she won, because the voters "were ashamed of Mr. Chamberlain's betrayal of Czechoslovakia and of democracy."[1] This was in reference to the Munich Pact, in which the United Kingdom under Prime Minister Chamberlain, accepted Nazi Germany's annexation of the Sudetenland in Czechoslovakia.[2]