The 20th New Brunswick Legislative Assembly represented New Brunswick between April 27, 1865 and May 9, 1866.
The assembly sat at the pleasure of the Governor of New Brunswick Arthur Charles Hamilton-Gordon.
Edwin A. Vail was chosen as speaker.
The Anti-Confederation Party led by Albert J. Smith formed the government.
In April 1866, the non-elected Legislative Council passed a reply to the throne speech supporting confederation, which was accepted by Governor Gordon. Smith and his government resigned to protest what they saw as an abuse of the principles of responsible government. The assembly was dissolved and an election was called.
| Electoral District | Name |
|---|---|
| St. John County | John W. Cudlip |
| Robert D. Wilmot | |
| Joseph Coram | |
| Timothy W. Anglin | |
| York | John C. Allen |
| George L. Hatheway | |
| John J. Fraser | |
| William H. Needham | |
| Westmorland | Albert J. Smith |
| Amand Landry | |
| Bliss Botsford | |
| William J. Gilbert | |
| King's | Edwin A. Vail |
| Walter B. Scovil | |
| George Otty | |
| Queen's | Joseph B. Perkins |
| Gideon D. Bailey | |
| Charlotte | George F. Hill |
| James Boyd | |
| Arthur Hill Gillmor | |
| Robert Thomson | |
| Northumberland | Edward Williston |
| Richard Hutchison | |
| George Kerr | |
| Richard Sutton | |
| Sunbury | John Glasier |
| William E. Perley | |
| Kent | William S. Caie |
| Lestock P. W. DesBrisay | |
| Gloucester | John Meahan |
| Robert Young | |
| Carleton | William Lindsay |
| Charles Connell | |
| Restigouche | John McMillan |
| Alexander C. DesBrisay | |
| Albert | Abner R. McClelan |
| John Lewis | |
| Victoria | John Costigan |
| Benjamin Beveridge | |
| City of St. John | Andrew R. Wetmore |
| Jacob V. Troop |
Notes:
| Preceded by 19th New Brunswick Legislative Assembly |
Legislative Assemblies of New Brunswick 1865-1866 |
Succeeded by 21st New Brunswick Legislative Assembly |