The ‘long road to adulthood’ that supposedly now characterizes the period from the teens to the late twenties (for individuals in developed countries) has been the subject of much recent media and academic commentary. This paper adopts a sociological perspective to review and critique this commentary, and in particular the argument made by certain developmental psychologists that the period between adolescence and fully-fledged adulthood is now distinct enough to constitute a new stage in the life cycle known as ‘emerging adulthood’. In contrast, it is argued that, rather than anything as significant as a new life stage, what is actually happening is the erosion of established ones. To illustrate this point, the article introduces the new theoretical concept of ‘life stage dissolution’ (and its attendant bi-directional processes of ‘adultification’ and ‘infantilization’) – a blurring (or more accurately merging) process that makes it increasingly difficult for young people to differentiate and disassociate themselves from the generation immediately ahead of them, and indeed vice versa. The paper argues that, whilst this process takes a number of cultural/psychosocial forms, it is at its most prominent in contemporary Anglo-American advertising and marketing practices that actively seek to erode traditionally demarcated adult and childhood roles, differences, and oppositions as a new and distinct message within contemporary consumerism.