Pittsburgh is the linguistic center of a dialect region within Midland American English, covering most of western Pennsylvania as well as parts of northern West Virginia, eastern Ohio, and a small area of western Maryland. Pittsburgh English is closely related to the Central Pennsylvania accent. The Pittsburgh dialect, often referred to as Pittsburghese (or Yinzbonics), contains substrates reflecting the ethnic heritage of the region: Scotch-Irish, German, and most prominently, Slavic. The distinctive features of the dialect emerged in the late 19th and early 20th centuries, when a large influx of immigrants arrived and found work in the booming steel industry. There are still vibrant ethnic communities in Pittsburgh, composed of both recent immigrants and third- or fourth-generation Americans, particularly in the South Side and Squirrel Hill, where it is not uncommon to hear people speaking Polish, Russian, and Serbo-Croatian. There are many heritage speakers of Eastern European languages, and some exclamations and babytalk expressions are common even among those who have otherwise been totally assimilated. There has also been significant influence, in the speech of younger Pittsburghers, from African American Vernacular English, especially in syntax.

With the advent of mass media, along with an influx of technology industry workers, certain localized vocabulary items are becoming less common, though still definitely noticeable; continuation and even some innovation are present among young people who feel a strong sense of local pride. Regional features in speech are heavily class-marked; working class Pittsburghers use far more local features than the upper middle class. Geographically, frequency of regional features is highest in the south and north, weakest in the center and east. Such generalizations are hard to make, however, due to the vast number of neighborhoods in Pittsburgh, their insular character, and irregular distribution, with some of the most conservative dialectic regions abutting the most deregionalized. (A note on terminology: Pittsburgh English is the proper name of the dialect. The term Pittsburghese, though in common use, is considered derogatory, and is most commonly used by Pittsburghers who eschew regional linguistic features; much to their chagrin, these people are quite likely to use the forms they stigmatize themselves.)