Chaparral Middle, Diamond Bar CA

Original Research by School Decision on Chaparral Middle

Chaparral Middle is a public middle school in Diamond Bar, California, serving grades six through eight in Walnut Valley Unified. It enrolls a little over one thousand students, drawn predominantly from a highly educated, affluent community where a large share of families are Asian American. The school's student body reflects its zip code: roughly three-quarters of students identify as Asian, with smaller shares identifying as Hispanic, white, or multiracial. About a quarter of students qualify for free or reduced-price lunch, a lower rate than many districts, and special-population data were not available in the records reviewed.

Chaparral's academic performance is a genuine strength. On California's state assessments, the school's overall proficiency index places it in the top quartile among middle schools across Los Angeles County's districts. Reading proficiency runs in the low-to-mid eighties across the grade span. Math proficiency climbs from the mid-seventies in sixth grade to the mid-eighties in seventh grade before settling in the high seventies in eighth grade. Seventh graders perform particularly strongly in both subjects. Science proficiency, tested only in eighth grade, sits in the mid-sixties, a softer point. The school has only one year of current assessment data, so trend analysis was not available; long-range growth or stability cannot be tracked from the figures provided.

Diamond Bar itself is a built-out suburban community of single-family homes and dispersed shopping centers, set on rolling hills east of Los Angeles. It is car-dependent, with no traditional downtown; the city is undertaking a long-term planning effort to create a more walkable mixed-use center, but the existing landscape is shaped by freeways and residential neighborhoods. The community is prosperous and middle- to upper-class. Housing values are well above state and national medians, and monthly housing costs as a share of typical household income run high, reflecting the affluent character of the area. The South Coast Air Quality Management District and the city government are among the largest local employers.

Chaparral is part of a district that has become notable in state education policy. Walnut Valley Unified has been California's largest receiver of District of Choice transfers, a program that allows families from outside district boundaries to enroll their children in WVUSD schools. In September 2025, California made that transfer program permanent, removing the prior uncertainty about whether families could rely on it year to year. That permanence is significant for anyone considering the district from outside its geographic boundaries.

The school's setting, student body composition, and academic profile together describe a middle school aligned with an affluent, academically oriented suburb. For families in or relocating to this area, Chaparral represents solid proficiency and a peer environment dominated by high-achieving households. Families transferring in from outside Diamond Bar via District of Choice may find it a credible option given the district's statewide standing and the newly permanent transfer pathway. The school does not have the breadth of specialized programs or enrichment details that appear in the publicly available record, so a parent may want to look into the full course and club offerings directly with the school to understand what lies beyond the core academic program.

See more original research from School Decision →

Academic performance

How students perform on state tests, by grade, set against the district.

Math

Grade 677%

School 77% · District 73% · ▲ 4 pts above district

▲ 46 pts above state median · ▲ 46 pts above county median

Grade 786%

School 86% · District 77% · ▲ 9 pts above district

▲ 56 pts above state median · ▲ 56 pts above county median

Grade 878%

School 78% · District 73% · ▲ 6 pts above district

▲ 50 pts above state median · ▲ 49 pts above county median

English language arts

Grade 679%

School 79% · District 77% · ▲ 3 pts above district

▲ 35 pts above state median · ▲ 35 pts above county median

Grade 789%

School 89% · District 81% · ▲ 8 pts above district

▲ 43 pts above state median · ▲ 43 pts above county median

Grade 881%

School 81% · District 79% · ▲ 2 pts above district

▲ 37 pts above state median · ▲ 35 pts above county median

Science

Grade 866%

School 66% · District 66% · ▲ 1 pts above district

▲ 41 pts above state median · ▲ 42 pts above county median

Social studies

Grade 879%

School 79% · District 81% · ▼ 2 pts below district

▲ 30 pts above state median · ▲ 31 pts above county median

This schoolWalnut Valley Unified, same grade

Graduation rate (ACGR) reflects the federally published Adjusted Cohort Graduation Rate for the most recent year available. We refresh this data annually at the close of each academic year in June. The federal source publishes a banded rate (for example, "90-94%") instead of an exact number for cohorts small enough to risk identifying individual students. The state distribution chart, where shown, plots every school in the state with a published rate or band; schools whose rate is federally suppressed are excluded. Where the federal source publishes a band rather than an exact rate, the school is placed within its band using a stable, ID-derived offset, so its position is consistent across visits.

Proficiency by household income

English language arts

Grade 6Lower-income74%Higher-income81%7 pp gap

Grade 7Lower-income87%Higher-income89%2 pp gap

Grade 8Lower-income77%Higher-income82%5 pp gap

Mathematics

Grade 6Lower-income75%Higher-income77%3 pp gap

Grade 7Lower-income86%Higher-income86%1 pp gap

Grade 8Lower-income72%Higher-income80%8 pp gap