Tallinn School No. 21
| Tallinn School No. 21 Tallinna 21. Kool  | |
|---|---|
The main building of the Tallinn School No. 21  | |
| Address | |
Raua 6 ,  | |
| Coordinates | 59°26′07″N 24°45′59″E / 59.4354°N 24.7664°E | 
| Information | |
| Type | Public | 
| Established | 1903 | 
| Principal | Meelis Kond | 
| Grades | 1–12 | 
| Number of pupils | 1385 | 
| Website | Official website | 
Tallinn School No. 21 is a secondary school in Tallinn, Estonia. The school was founded as the Tallinn kroonualgkool No. 21. The first schoolhouse was a wooden house on J. Poska 6a. In the 1923/24 academic year, as the number of students grew, a new schoolhouse was needed.
The school is a member of the G5 Union of Schools, which comprises what some call the "elite Tallinn city centre schools": Tallinn English College, Tallinn French School, Gustav Adolf Grammar School, and Tallinn School No. 21.