[3][4] Quercus engelmannii is a small tree growing to 10 metres (33 feet) tall, generally evergreen, but may be drought-deciduous during the hot, dry local summers, and has a rounded or elliptical canopy.

The leaves are leathery, 3–6 centimetres (1+1⁄4–2+1⁄4 inches) long and 1–2 cm (1⁄2–3⁄4 in) broad, of a blue-green color, and may be flat or wavy, with smooth margins.

The Engelmann oak ranges from the foothills of the San Gabriel Mountains in eastern Los Angeles County through the Santa Ana Mountains of Orange County and the western foothills and mesas of the Peninsular Ranges in Riverside and San Diego counties, extending into the Sierra Juárez and Sierra de San Pedro Mártir ranges of northern Baja California.

It is generally found in savannas and woodlands above the dry coastal plain, but below the 1,300 m (4,300 ft) elevation where colder winters prevail.

[2] Fossil evidence shows that Engelmann oaks once had a wider range, extending through what is now the Mojave and Sonoran deserts into eastern California and Arizona.