Top 100 largest schools in Ontario (2025)

Schools with the highest enrolment. Ordered by the measure shown, with the Success Index (Canada) for context; 100 schools shown.

#	School	Sector	Enrolment	Success Index (Canada)	Key result	Students
1	Bishop Paul Francis Reding Catholic Secondary School Milton · Secondary · Grades 9-12	Catholic	2,660	76.3 Top 25%	92% OSSLT pass rate	2,660
2	St Mary's High School Kitchener · Secondary · Grades 9-12	Catholic	2,240	47.4 Lower 50%	94% OSSLT pass rate	2,240
3	White Oaks Secondary School Oakville · Secondary · Grades 9-12	Public	2,180	85.3 Top 5%	96% OSSLT pass rate	2,180
4	Earl Haig Secondary School North York · Secondary · Grades 9-12	Public	2,175	77.9 Top 25%	95% OSSLT pass rate	2,175
5	Bishop Ryan Catholic Secondary School Hannon · Secondary · Grades 9-12	Catholic	2,115	50.0 Lower 50%	85% OSSLT pass rate	2,115
6	John F Ross Collegiate and Vocational Institute Guelph · Secondary · Grades 9-12	Public	2,115	76.5 Top 25%	90% OSSLT pass rate	2,115
7	Northern Secondary School Toronto · Secondary · Grades 9-12	Public	2,075	74.0 Top 25%	91% OSSLT pass rate	2,075
8	Bill Hogarth Secondary School Markham · Secondary · Grades 9-12	Public	2,055	82.3 Top 10%	97% OSSLT pass rate	2,055
9	Michael Power/St Joseph High School Toronto · Secondary · Grades 9-12	Catholic	2,035	64.3 Top 50%	87% OSSLT pass rate	2,035
10	J Clarke Richardson Collegiate Institute Ajax · Secondary · Grades 9-12	Public	2,010	59.1 Top 50%	83% OSSLT pass rate	2,010
11	Saunders Secondary School London · Secondary · Grades 9-12	Public	2,010	24.9 Lower 50%	70% OSSLT pass rate	2,010
12	St Benedict Catholic Secondary School Cambridge · Secondary · Grades 9-12	Catholic	1,955	53.1 Top 50%	90% OSSLT pass rate	1,955
13	Bayview Secondary School Richmond Hill · Secondary · Grades 9-12	Public	1,940	80.5 Top 10%	95% OSSLT pass rate	1,940
14	Resurrection Catholic Secondary School Kitchener · Secondary · Grades 9-12	Catholic	1,920	49.8 Lower 50%	90% OSSLT pass rate	1,920
15	St Francis Xavier Secondary School Mississauga · Secondary · Grades 9-12	Catholic	1,890	72.1 Top 25%	91% OSSLT pass rate	1,890
16	Pickering High School Ajax · Secondary · Grades 9-12	Public	1,870	73.3 Top 25%	93% OSSLT pass rate	1,870
17	Fletcher's Meadow Secondary School Brampton · Secondary · Grades 9-12	Public	1,870	35.9 Lower 50%	81% OSSLT pass rate	1,870
18	Assumption College School High School Brantford · Secondary · Grades 9-12	Catholic	1,865	55.8 Top 50%	91% OSSLT pass rate	1,865
19	Mayfield Secondary School Caledon · Secondary · Grades 9-12	Public	1,865	63.7 Top 50%	92% OSSLT pass rate	1,865
20	Bur Oak Secondary School Markham · Secondary · Grades 9-12	Public	1,865	80.5 Top 10%	96% OSSLT pass rate	1,865
21	Pierre Elliott Trudeau High School Markham · Secondary · Grades 9-12	Public	1,865	79.5 Top 25%	97% OSSLT pass rate	1,865
22	Unionville High School Unionville · Secondary · Grades 9-12	Public	1,865	68.1 Top 25%	90% OSSLT pass rate	1,865
23	St Edmund Campion Secondary School Brampton · Secondary · Grades 9-12	Catholic	1,810	63.7 Top 50%	84% OSSLT pass rate	1,810
24	St. Thomas More Catholic Secondary School Hamilton · Secondary · Grades 9-12	Catholic	1,810	32.8 Lower 50%	80% OSSLT pass rate	1,810
25	Mother Teresa Catholic Secondary School London · Secondary · Grades 9-12	Catholic	1,795	55.7 Top 50%	90% OSSLT pass rate	1,795
26	Holy Trinity Catholic Secondary School Oakville · Secondary · Grades 9-12	Catholic	1,775	70.0 Top 25%	88% OSSLT pass rate	1,775
27	St. Francis Xavier Catholic Secondary School Milton · Secondary · Grades 9-12	Catholic	1,770	58.1 Top 50%	85% OSSLT pass rate	1,770
28	Maxwell Heights Secondary School Oshawa · Secondary · Grades 9-12	Public	1,765	61.7 Top 50%	91% OSSLT pass rate	1,765
29	Castlebrooke Secondary School Brampton · Secondary · Grades 9-12	Public	1,765	60.9 Top 50%	90% OSSLT pass rate	1,765
30	Cameron Heights Collegiate Institute Kitchener · Secondary · Grades 9-12	Public	1,765	62.8 Top 50%	90% OSSLT pass rate	1,765
31	Laurel Heights Secondary School Waterloo · Secondary · Grades 9-12	Public	1,765	71.9 Top 25%	87% OSSLT pass rate	1,765
32	Craig Kielburger Secondary School Milton · Secondary · Grades 9-12	Public	1,760	67.9 Top 50%	84% OSSLT pass rate	1,760
33	Marc Garneau Collegiate Institute Toronto · Secondary · Grades 9-12	Public	1,755	9.0 Lower 50%	72% OSSLT pass rate	1,755
34	Vincent Massey Secondary School Windsor · Secondary · Grades 9-12	Public	1,750	57.9 Top 50%	89% OSSLT pass rate	1,750
35	Harold M. Brathwaite Secondary School Brampton · Secondary · Grades 9-12	Public	1,745	71.8 Top 25%	93% OSSLT pass rate	1,745
36	Guelph Collegiate and Vocational Institute Guelph · Secondary · Grades 9-12	Public	1,735	68.3 Top 25%	91% OSSLT pass rate	1,735
37	Stephen Lewis Secondary School Thornhill · Secondary · Grades 9-12	Public	1,730	86.2 Top 5%	92% OSSLT pass rate	1,730
38	St Marcellinus Secondary School Mississauga · Secondary · Grades 9-12	Catholic	1,715	76.6 Top 25%	91% OSSLT pass rate	1,715
39	Earl of March Secondary School Kanata · Secondary · Grades 9-12	Public	1,715	84.1 Top 10%	95% OSSLT pass rate	1,715
40	John Fraser Secondary School Mississauga · Secondary · Grades 9-12	Public	1,715	81.9 Top 10%	95% OSSLT pass rate	1,715
41	St Robert Catholic High School Thornhill · Secondary · Grades 9-12	Catholic	1,705	83.8 Top 10%	96% OSSLT pass rate	1,705
42	David Suzuki Secondary School Brampton · Secondary · Grades 9-12	Public	1,700	38.2 Lower 50%	81% OSSLT pass rate	1,700
43	St. Francis Xavier (9-12) Catholic School Gloucester · Secondary · Grades 9-12	Catholic	1,665	52.3 Top 50%	81% OSSLT pass rate	1,665
44	West Niagara Secondary School Lincoln · Secondary · Grades 9-12	Public	1,655	74.8 Top 25%	88% OSSLT pass rate	1,655
45	Sinclair Secondary School Whitby · Secondary · Grades 9-12	Public	1,655	73.1 Top 25%	90% OSSLT pass rate	1,655
46	Garth Webb Secondary School Oakville · Secondary · Grades 9-12	Public	1,655	86.1 Top 5%	94% OSSLT pass rate	1,655
47	Centennial Collegiate and Vocational Institute Guelph · Secondary · Grades 9-12	Public	1,655	81.7 Top 10%	93% OSSLT pass rate	1,655
48	Cathedral High School Hamilton · Secondary · Grades 9-12	Catholic	1,650	12.2 Lower 50%	64% OSSLT pass rate	1,650
49	Longfields Davidson Heights Secondary School Nepean · Secondary · Grades 9-12	Public	1,650	69.3 Top 25%	87% OSSLT pass rate	1,650
50	Kitchener Waterloo Collegiate and Vocational School Kitchener · Secondary · Grades 9-12	Public	1,650	61.7 Top 50%	88% OSSLT pass rate	1,650
51	Tommy Douglas Secondary School Woodbridge · Secondary · Grades 9-12	Public	1,645	71.6 Top 25%	92% OSSLT pass rate	1,645
52	St. John Henry Newman Catholic Secondary School Stoney Creek · Secondary · Grades 9-12	Catholic	1,640	65.5 Top 50%	90% OSSLT pass rate	1,640
53	Richmond Hill High School Richmond Hill · Secondary · Grades 9-12	Public	1,635	81.4 Top 10%	96% OSSLT pass rate	1,635
54	Dunbarton High School Pickering · Secondary · Grades 9-12	Public	1,630	71.7 Top 25%	86% OSSLT pass rate	1,630
55	St Aloysius Gonzaga Secondary School Mississauga · Secondary · Grades 9-12	Catholic	1,625	71.5 Top 25%	89% OSSLT pass rate	1,625
56	St. Jean de Brebeuf Catholic Secondary School Hamilton · Secondary · Grades 9-12	Catholic	1,615	32.1 Lower 50%	78% OSSLT pass rate	1,615
57	Riverdale Collegiate Institute Toronto · Secondary · Grades 9-12	Public	1,600	80.1 Top 10%	95% OSSLT pass rate	1,600
58	Robert F Hall Catholic Secondary School Caledon East · Secondary · Grades 9-12	Catholic	1,595	63.2 Top 50%	90% OSSLT pass rate	1,595
59	Milliken Mills High School Unionville · Secondary · Grades 9-12	Public	1,595	60.0 Top 50%	90% OSSLT pass rate	1,595
60	Sir Frederick Banting Secondary School London · Secondary · Grades 9-12	Public	1,590	36.0 Lower 50%	78% OSSLT pass rate	1,590
61	St Theresa of Lisieux Catholic High School Richmond Hill · Secondary · Grades 9-12	Catholic	1,590	88.0 Top 5%	97% OSSLT pass rate	1,590
62	Maple High School Maple · Secondary · Grades 9-12	Public	1,590	74.1 Top 25%	93% OSSLT pass rate	1,590
63	Iroquois Ridge High School Oakville · Secondary · Grades 9-12	Public	1,585	84.8 Top 10%	94% OSSLT pass rate	1,585
64	Northview Heights Secondary School Toronto · Secondary · Grades 9-12	Public	1,585	46.0 Lower 50%	86% OSSLT pass rate	1,585
65	St Augustine Catholic High School Markham · Secondary · Grades 9-12	Catholic	1,575	81.8 Top 10%	96% OSSLT pass rate	1,575
66	Bill Crothers Secondary School Unionville · Secondary · Grades 9-12	Public	1,575	84.7 Top 10%	98% OSSLT pass rate	1,575
67	Markville Secondary School Markham · Secondary · Grades 9-12	Public	1,575	78.8 Top 25%	96% OSSLT pass rate	1,575
68	Georgetown District High School Georgetown · Secondary · Grades 9-12	Public	1,565	74.6 Top 25%	85% OSSLT pass rate	1,565
69	Grand River Collegiate Institute Kitchener · Secondary · Grades 9-12	Public	1,560	51.7 Top 50%	83% OSSLT pass rate	1,560
70	Sacred Heart High School Stittsville · Secondary · Grades 9-12	Catholic	1,555	81.6 Top 10%	95% OSSLT pass rate	1,555
71	Forest Heights Collegiate Institute Kitchener · Secondary · Grades 9-12	Public	1,555	38.7 Lower 50%	86% OSSLT pass rate	1,555
72	John McCrae Secondary School Nepean · Secondary · Grades 9-12	Public	1,550	62.9 Top 50%	83% OSSLT pass rate	1,550
73	Christ the King Catholic Secondary School Georgetown · Secondary · Grades 9-12	Catholic	1,545	63.2 Top 50%	84% OSSLT pass rate	1,545
74	Milton District High School Milton · Secondary · Grades 9-12	Public	1,535	77.3 Top 25%	92% OSSLT pass rate	1,535
75	St Joseph High School Nepean · Secondary · Grades 9-12	Catholic	1,535	65.7 Top 50%	86% OSSLT pass rate	1,535
76	Westdale Secondary School Hamilton · Secondary · Grades 9-12	Public	1,525	48.6 Lower 50%	88% OSSLT pass rate	1,525
77	H B Beal Secondary School London · Secondary · Grades 9-12	Public	1,525	33.3 Lower 50%	79% OSSLT pass rate	1,525
78	Cardinal Ambrozic Catholic Secondary School Brampton · Secondary · Grades 9-12	Catholic	1,520	61.7 Top 50%	91% OSSLT pass rate	1,520
79	Dr G W Williams Secondary School Aurora · Secondary · Grades 9-12	Public	1,515	84.2 Top 10%	94% OSSLT pass rate	1,515
80	Newmarket High School Newmarket · Secondary · Grades 9-12	Public	1,515	84.1 Top 10%	97% OSSLT pass rate	1,515
81	Collingwood Collegiate Institute Collingwood · Secondary · Grades 9-12	Public	1,510	48.6 Lower 50%	84% OSSLT pass rate	1,510
82	St Jean de Brebeuf Catholic High School Woodbridge · Secondary · Grades 9-12	Catholic	1,510	54.9 Top 50%	85% OSSLT pass rate	1,510
83	Danforth Collegiate Institute and Technical School Toronto · Secondary · Grades 9-12	Public	1,500	36.2 Lower 50%	78% OSSLT pass rate	1,500
84	Middlefield Collegiate Institute Markham · Secondary · Grades 9-12	Public	1,500	55.3 Top 50%	86% OSSLT pass rate	1,500
85	A B Lucas Secondary School London · Secondary · Grades 9-12	Public	1,495	66.6 Top 50%	85% OSSLT pass rate	1,495
86	St Patrick's Catholic High School Sarnia · Secondary · Grades 9-12	Catholic	1,480	61.4 Top 50%	87% OSSLT pass rate	1,480
87	Waterloo Collegiate Institute Waterloo · Secondary · Grades 9-12	Public	1,480	44.2 Lower 50%	85% OSSLT pass rate	1,480
88	Banting Memorial High School Alliston · Secondary · Grades 9-12	Public	1,475	58.9 Top 50%	87% OSSLT pass rate	1,475
89	Barrie North Collegiate Institute Barrie · Secondary · Grades 9-12	Public	1,475	43.9 Lower 50%	88% OSSLT pass rate	1,475
90	Nantyr Shores Secondary School Innisfil · Secondary · Grades 9-12	Public	1,470	42.4 Lower 50%	82% OSSLT pass rate	1,470
91	St. Andre Bessette Secondary School London · Secondary · Grades 9-12	Catholic	1,465	63.4 Top 50%	90% OSSLT pass rate	1,465
92	Bishop Allen Academy Catholic Secondary School Toronto · Secondary · Grades 9-12	Catholic	1,460	82.3 Top 10%	94% OSSLT pass rate	1,460
93	Agincourt Collegiate Institute Agincourt · Secondary · Grades 9-12	Public	1,460	63.2 Top 50%	90% OSSLT pass rate	1,460
94	Humberside Collegiate Institute Toronto · Secondary · Grades 9-12	Public	1,460	85.2 Top 5%	96% OSSLT pass rate	1,460
95	Waterloo-Oxford District Secondary School Baden · Secondary · Grades 9-12	Public	1,460	59.2 Top 50%	84% OSSLT pass rate	1,460
96	Huron Heights Secondary School Kitchener · Secondary · Grades 9-12	Public	1,455	62.6 Top 50%	88% OSSLT pass rate	1,455
97	Merivale High School Nepean · Secondary · Grades 9-12	Public	1,440	79.9 Top 10%	96% OSSLT pass rate	1,440
98	Medway High School Arva · Secondary · Grades 9-12	Public	1,435	69.5 Top 25%	84% OSSLT pass rate	1,435
99	Western Technical & Commercial School Toronto · Secondary · Grades 9-12	Public	1,435	44.0 Lower 50%	83% OSSLT pass rate	1,435
100	Brampton Centennial Secondary School Brampton · Secondary · Grades 9-12	Public	1,430	48.0 Lower 50%	88% OSSLT pass rate	1,430

Bishop Paul Francis Reding Catholic Secondary School in Milton leads the 2025 list of largest schools in Ontario with Enrolment 2,660. Of the 100 schools shown, 69 are public, 31 are catholic.

Use the rankings to build a shortlist, then visit the schools and ask how they support students at your child's level.

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Frequently asked questions

What is the best largest school in Ontario?

Bishop Paul Francis Reding Catholic Secondary School in Milton ranks first among largest schools in Ontario with Enrolment 2,660 (Enrolment: 2,660).

How are largest schools in Ontario ranked?

Schools with the highest enrolment. Only schools eligible for the Success Index (Canada) are included; the index is shown alongside for context.

Are these 2025 rankings official?

No. They are computed by Success Tutoring from official Canadian data (Ontario – School information and student demographics; BC Data Catalogue – Foundation Skills Assessment). Provinces publish different assessments, so scores are comparable within a province, not between provinces.