| St. Theresa's Catholic High School | |
| Address: | 347 Galloway Blvd. |
| City: | Midland |
| Province: | Ontario |
| Postcode: | L4R 5B2 |
| Country: | Canada |
| Schooltype: | Separate high school |
| Founded: | 1958 |
| Schoolboard: | Simcoe Muskoka Catholic District School Board |
| Principal: | Karen McNamara |
| Grades Label: | Grades |
| Grades: | 9 to 12 |
| Enrollment: | 700 |
| Enrollment As Of: | 2020 |
| Language: | English |
| Colours: | Blue & White |
| Mascot: | Storm the Thunderwolf |
| Team Name: | St. Theresa's Thunderwolves |
St. Theresa's High School is a high school in Midland, Ontario, Canada administered by the Simcoe Muskoka Catholic District School Board. The school serves students from Midland, Penetanguishene, Tay Township, Tiny Township and a portion of Springwater Township (Elmvale). The current enrollment is 700 students from grade 9–12. The current administration consists of principal Karen McNamara and vice principal Theresa Noga-McArthur.The school was founded in 1958. It has been in its current building since 1992, and has added two additions to the building since then.