Largest Schools in Ontario (2025)

Schools with the highest enrollment. Ranked by the Success Index (US) from official American data; 34 schools in Ontario, California. Rank positions shown on each profile are within United States and California.

#	School	Sector	Enrollment	Success Index (US)	Key result	Students
1	Chaffey High Ontario · High · Grades 9–12	Public	3,127	24.8 Lower 50%	20% Math proficiency	3,127
2	Colony High Ontario · High · Grades 9–12	Public	2,109	38.7 Lower 50%	35% Math proficiency	2,109
3	Ontario High Ontario · High · Grades 9–12	Public	1,994	28.1 Lower 50%	27% Math proficiency	1,994
4	Park View Elementary Ontario · Elementary · Grades K–6	Public	844	49.8 Lower 50%	34.4% Free/reduced-price lunch	844
5	Ranch View Elementary Ontario · Elementary · Grades K–6	Public	738	50.5 Top 50%	48% Math proficiency	738
6	Edison Elementary Ontario · Elementary · Grades K–8	Public	736	54.8 Top 50%	60% Math proficiency	736
7	Central Language Academy Ontario · Elementary · Grades K–8	Public	736	31.8 Lower 50%	27% Math proficiency	736
8	Ray Wiltsey Middle Ontario · Middle · Grades 6–8	Public	727	20.0 Lower 50%	25% Math proficiency	727
9	Oaks Middle Ontario · Middle · Grades 7–8	Public	668	28.8 Lower 50%	31% Math proficiency	668
10	Richard Haynes Elementary Ontario · Elementary · Grades K–6	Public	641	24.9 Lower 50%	34% Math proficiency	641
11	Berlyn Elementary Ontario · Elementary · Grades K–6	Public	639	13.4 Lower 50%	22% Math proficiency	639
12	Grace Yokley Junior High Ontario · Middle · Grades 7–8	Public	606	38.8 Lower 50%	33% Math proficiency	606
13	Bon View Elementary Ontario · Elementary · Grades K–6	Public	598	18.4 Lower 50%	27% Math proficiency	598
14	Sultana Elementary Ontario · Elementary · Grades K–6	Public	589	33.7 Lower 50%	41% Math proficiency	589
15	Ontario Center Ontario · Elementary · Grades K–5	Public	585	28.1 Lower 50%	31% Math proficiency	585
16	Liberty Elementary Ontario · Elementary · Grades K–6	Public	578	44.6 Lower 50%	51% Math proficiency	578
17	Euclid Elementary Ontario · Elementary · Grades K–6	Public	572	25.3 Lower 50%	35% Math proficiency	572
18	Mission Elementary Ontario · Elementary · Grades K–6	Public	571	25.7 Lower 50%	37% Math proficiency	571
19	Creek View Elementary Ontario · Elementary · Grades K–6	Public	566	29.0 Lower 50%	30% Math proficiency	566
20	Mountain View Elementary Ontario · Elementary · Grades K–6	Public	564	35.2 Lower 50%	36% Math proficiency	564
21	Vineyard Elementary Ontario · Elementary · Grades K–8	Public	562	29.9 Lower 50%	36% Math proficiency	562
22	Hawthorne Elementary Ontario · Elementary · Grades K–6	Public	549	22.9 Lower 50%	29% Math proficiency	549
23	Elderberry Elementary Ontario · Elementary · Grades K–6	Public	544	37.7 Lower 50%	52% Math proficiency	544
24	Vina Danks Middle Ontario · Middle · Grades 7–8	Public	544	23.3 Lower 50%	23% Math proficiency	544
25	Mariposa Elementary Ontario · Elementary · Grades K–6	Public	537	15.4 Lower 50%	24% Math proficiency	537
26	Lincoln Elementary Ontario · Elementary · Grades K–6	Public	530	26.3 Lower 50%	37% Math proficiency	530
27	De Anza Middle Ontario · Middle · Grades 7–8	Public	510	22.0 Lower 50%	26% Math proficiency	510
28	Arroyo Elementary Ontario · Elementary · Grades K–8	Public	493	23.1 Lower 50%	29% Math proficiency	493
29	El Camino Elementary Ontario · Elementary · Grades K–6	Public	476	21.0 Lower 50%	29% Math proficiency	476
30	Del Norte Elementary Ontario · Elementary · Grades K–6	Public	428	21.2 Lower 50%	30% Math proficiency	428
31	Corona Elementary Ontario · Elementary · Grades K–6	Public	414	25.9 Lower 50%	38% Math proficiency	414
32	Levi H. Dickey Elementary Ontario · Elementary · Grades K–6	Public	413	17.7 Lower 50%	23% Math proficiency	413
33	Vista Grande Elementary Ontario · Elementary · Grades K–6	Public	358	42.6 Lower 50%	49% Math proficiency	358
34	Woodcrest Junior High Ontario · Middle · Grades 7–8	Public	324	32.5 Lower 50%	34% Math proficiency	324

Chaffey High in Ontario leads the 2025 list of largest schools in Ontario with Enrollment 3,127. Of the 34 schools shown, 34 are public.

For the full picture see the wider California largest schools rankings, every school on the Ontario page, or the comparison tool to put a shortlist side by side.

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Frequently asked questions

What is the best largest school in Ontario?

Chaffey High in Ontario, California ranks first among largest schools in Ontario with Enrollment 3,127 (Enrollment: 3,127).

How are largest schools in Ontario ranked?

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

Are these 2025 rankings official?

No. They are computed by Success Tutoring from official American data (Urban Institute Education Data Portal (NCES CCD, EDFacts); NCES Common Core of Data). States set their own assessments and proficiency cut scores, so proficiency rates are most comparable within a state. Use the state rankings for like-for-like comparisons.