| 1 | Boston High School | 816 pupils | Grammar · Day · 6th | Boston, East Midlands | — |
| 2 | Bourne Grammar School | Good | Grammar · Day · 6th | Bourne, East Midlands | Good |
| 3 | Caistor Grammar School | Good | Grammar · Day · 6th | Market Rasen, East Midlands | Good |
| 4 | Carre's Grammar School | Good | Grammar · Day · 6th | Sleaford, East Midlands | Good |
| 5 | Kesteven and Grantham Girls' School | Outstanding | Grammar · Day · 6th | Grantham, East Midlands | Outstanding |
| 6 | Kesteven and Sleaford High School Selective Academy | 756 pupils | Grammar · Day · 6th | Sleaford, East Midlands | — |
| 7 | King Edward VI Grammar School | Good | Grammar · Day · 6th | Louth, East Midlands | Good |
| 8 | Queen Elizabeth's Grammar Alford - A Selective Academy | Good | Grammar · Day · 6th | Alford, East Midlands | Good |
| 9 | Queen Elizabeth's Grammar School, Horncastle | Good | Grammar · Day · 6th | Horncastle, East Midlands | Good |
| 10 | Skegness Grammar School | Good | Grammar · Day · 6th | Skegness, East Midlands | Good |
| 11 | Spalding Grammar School | Good | Grammar · Day · 6th | Spalding, East Midlands | Good |
| 12 | Spalding High School | Outstanding | Grammar · Day · 6th | Spalding, East Midlands | Outstanding |
| 13 | The Boston Grammar School | Good | Grammar · Day · 6th | Boston, East Midlands | Good |
| 14 | The King's School, Grantham | Good | Grammar · Day · 6th | Grantham, East Midlands | Good |
| 15 | The Queen Elizabeth's High School, Gainsborough | Good | Grammar · Day · 6th | Gainsborough, East Midlands | Good |