Pinus radiata (family Pinaceae) is known in English as Monterey Pine in some parts of the world (mainly in the USA and Britain), and Radiata Pine in others (primarily Australia and New Zealand). It is a species of pine native to coastal southern California in three very limited areas in Santa Cruz, Monterey and San Luis Obispo Counties, and (as the variety Pinus radiata var. binata) on Guadalupe Island and Cedros Island off the west coast of Baja California, Mexico. It is also extensively cultivated in many other warm temperate parts of the world.

P. radiata grows to between 15-30 m in height in the wild, but up to 60 m in cultivation in optimum conditions, with upward pointing branches and a rounded top. The leaves ('needles') are bright green, in clusters of three (two in var. binata), slender, 8-15 cm long and with a blunt tip. The cones are 7-17 cm long, brown, egg-shaped (ovoid), and usually set asymmetrically on a branch, attached at an oblique angle. The bark is fissured and dark grey to brown.

It is closely related to Bishop Pine and Knobcone Pine, hybridising readily with both species; it is distinguished from the former by needles in threes (not pairs), and from both by the cones not having a sharp spine on the scales.

In the wild, Monterey Pine in California is seriously threatened by an introduced fungal disease, Pine Pitch Canker, caused by Fusarium circinatum, while var. binata on Guadalupe Island is critically endangered (less than 100 surviving trees) by uncontrolled grazing by goats released long ago on this uninhabited island.

It is a fast-growing tree, adaptable to a broad range of soil types and climates, though does not tolerate temperatures below about -15°C. Its fast growth makes it ideal for forestry; in a good situation, P. radiata can reach its full height in 40 years or so. It was first introduced into New Zealand in the 1850s; today, over 90% of the country's plantation forests are of this species. This includes the Kaingaroa Forest on the central plateau of the North Island which is the largest planted forest in the world. Australia also has massive Radiata Pine plantations; so much so that many Australians are concerned by the resulting loss of native wildlife habitat. A few native animals, however, thrive on P. radiata, notably the Yellow-tailed Black Cockatoo which, although deprived of much of its natural diet by massive habitat alteration, feeds on P. radiata seeds. P. radiata has also been introduced to the Valdivian temperate rain forests of southern Chile, where vast plantations have been planted for timber, again displacing the native forests.

In areas such as New Zealand this tree has become naturalized, and is considerd a weed in the native forest habitat where it has escaped from plantations.