William S. Hart Union High

Santa Clarita, California · 21,011 students · 16 schools

Enrollment

21,011

Schools

Location

Santa Clarita, California

COSMIQ projected accountability rating

Near average

on California's per-indicator accountability scale

Confidence 94% Data completeness 100% Based on 2023–24 data

This is an independent estimate generated by COSMIQ's open Rating Predictor from public math & reading proficiency — it is not an official California rating, and states weight many additional factors.

How this is calculated →Run the live predictor →

Proficiency trend

Percent of students proficient on the state assessment.

School year	Math	Reading / ELA
2024–25	48.7%	69.8%

Where this district could improve

Math proficiency
Worth 50% of the formula; you're at 40% of max points.
ELA proficiency
Worth 50% of the formula; you're at 60% of max points.

Schools in this district

Saugus HighSaugus, CA 2,378 students Valencia HighValencia, CA 2,275 students Golden Valley HighSanta Clarita, CA 2,073 students William S. Hart HighNewhall, CA 2,034 students Canyon HighCanyon Country, CA 1,946 students West Ranch HighValencia, CA 1,865 students Arroyo Seco Junior HighValencia, CA 1,217 students Castaic HighCastaic, CA 1,208 students Rio Norte Junior HighSanta Clarita, CA 1,123 students La Mesa Junior HighSanta Clarita, CA 1,014 students Sierra Vista Junior HighCanyon Country, CA 991 students Placerita Junior HighNewhall, CA 888 students Rancho Pico Junior HighStevenson Ranch, CA 790 students

Methodology & sources

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<figure style="font-family:system-ui,-apple-system,sans-serif;border:1px solid #e2e8f0;border-radius:12px;padding:20px 22px;max-width:480px;background:#ffffff;color:#0f172a;margin:0;line-height:1.4"><div style="font-size:15px;font-weight:700">William S. Hart Union High</div><div style="font-size:13px;color:#64748b;margin-top:3px">Santa Clarita, California &middot; Public school district</div><div style="display:flex;flex-wrap:wrap;margin-top:14px"><div style="margin-right:20px"><div style="font-size:11px;text-transform:uppercase;letter-spacing:.04em;color:#94a3b8;margin-bottom:2px">Enrollment</div><div style="font-size:22px;font-weight:700;color:#0f172a">21,011</div></div><div><div style="font-size:11px;text-transform:uppercase;letter-spacing:.04em;color:#94a3b8;margin-bottom:2px">Projected Rating (per-indicator)</div><div style="font-size:22px;font-weight:700;color:#0f172a">Near average</div></div></div><figcaption style="font-size:11px;color:#94a3b8;margin-top:14px;padding-top:12px;border-top:1px solid #f1f5f9">Data: NCES / EDFacts (2024 data) &middot; <a href="https://getcosmiq.app/schools/CA/william-s-hart-union-high" style="color:#0891b2;text-decoration:none" target="_blank" rel="noopener">View full profile on COSMIQ &#8594;</a></figcaption></figure>

Cite this page

COSMIQ. (2026). William S. Hart Union High — school district profile. Retrieved August 23, 2026, from https://getcosmiq.app/schools/CA/william-s-hart-union-high

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About this profile. COSMIQ is an independent, free AI tutoring service and is not affiliated with, endorsed by, or sponsored by William S. Hart Union High, California, or any government education agency. All figures are drawn from public U.S. Department of Education data (NCES Common Core of Data and EDFacts). Any projected rating is an independent estimate, not an official score. COSMIQ does not collect or publish user reviews or ratings of schools.

Data last refreshed August 7, 2026.