Chapter 5 moves beyond regional accents to the importance of speech sound patterns for speakers’ presentations of their affiliations and for listeners’ interpretations of others.The chapter considers what sociophonetics offers the understanding of language and the social world and outlines some of the fundamental ways that the major social categories of social class, gender, ethnicity and age impact phonetic variation and change.Taking each of these topics in turn, the chapter unpacks how sociolinguistic studies of socially driven variation have established a foundation that underpins contemporary sociophonetic research and then transitions to survey sociophonetic research that investigates the influence of these four social factors on speech production.The chapter then turns to the role of these factors in speech processing, providing an overview of how factors such as class, gender and ethnicity have been shown to affect how listeners process variation in speech.The chapter closes with a discussion of how such research has contributed greatly to our understanding of how social factors correlate with linguistic factors.