California English (or Californian English) is the collection of English dialects native to California, traditionally classified under General or Western American English.

As California became more diverse, English speakers from a wide variety of backgrounds began to pick up different linguistic elements from one another and also developed new ones; the result is both divergence and convergence within California English. Overall, linguists who studied English around World War II tended to find few, if any, patterns unique to the state. Studies in the 1950s and 1960s largely only commented on the increasingly common cot–caught merger within the state.

In the 1980s, linguists first noted a distinctive chain shift of vowel sounds, the California Vowel Shift, used by young people in southern California and the San Francisco Bay Area of northern California. This helped to define an accent emerging primarily among youthful, white, urban, coastal speakers, and popularly associated with the valley girl and surfer youth subcultures. The possibility that this is, in fact, an age-specific variety of English is one hypothesis; however, certain features of this accent are intensifying and spreading geographically.

Other documented California English includes a "country" accent associated with rural and inland white Californians, which is also (to a lesser extent) affected by the California Vowel Shift; an older accent once spoken by Irish Americans in San Francisco; and distinctly Californian varieties of Chicano English mainly associated with Mexican Americans. Research has shown that Californians themselves perceive a linguistic boundary between northern and southern California, particularly regarding the northern use of hella and southern (but now nationally widespread) use of dude, bro, and like.

Varieties of English most popularly associated with California largely correlate with the major urban areas along the coast. Notable is the absence of a distinct /ɔ/ phoneme (the vowel sound of caught, stalk, clawed, etc.), which has completely merged with /ɑ/ (the vowel sound of cot, stock, clod, etc.), as in most of the Western United States.

A few phonological processes have been identified as being particular to urban and coastal California English. However, these vowel changes are by no means universal in Californian speech, and any single Californian's speech may only have some or none of the changes identified below. These sounds might also be found in the speech of some people from areas outside of California.

One topic that has begun to receive much attention from scholars in recent decades has been the emergence of a vowel-based chain shift in California (with a similar pattern now reported nationwide and known as the low back merger shift). The image in this section illustrates the California vowel shift on a vowel chart. The vowel space of the image is a cross-section (as if looking at the interior of a mouth from a side profile perspective); it is a rough approximation of the space in a human mouth where the tongue is located in articulating certain vowel sounds (the left is the front of the mouth closer to the teeth, the right side of the chart being the back of the mouth). As with other vowel shifts, several vowels may be seen moving in a chain shift around the mouth. As one vowel encroaches upon the space of another, the adjacent vowel in turn experiences a movement in order to maximize phonemic differentiation.

For convenience, California English will be compared with a "typical" General American English, abbreviated "GA". /ɪ/ is pulled towards [ɛ] (bit and miss are sounding more like how other dialects realize bet and mess), /ɛ/ is pulled towards [æ] (wreck and kettle are sounding more like rack and cattle), /æ/ is pulled towards [ä], and /ɑ/ and /ɔ/ merge (cot and stock are sounding more like caught and stalk): the cot-caught merger.