The understanding of modern young people's conceptions of adulthood has largely been informed and constructed through the lens of the theory of emerging adulthood. As a consequence, a relatively unquestioned belief is that there has been a trend towards the gradual development of internal, subjective characteristics and away from the attainment of traditional adult roles in emerging adults' conceptions of adulthood. Using both quantitative and qualitative methods, we surveyed Australian university students about their understanding of what it means to be an adult. Exploratory factor analysis of the Criteria for Adulthood Scale emphasised family capacities, demographic markers, norm compliance, and “novelty of adulthood,” while qualitative themes emphasised both personal and environmental characteristics. We suggest that rather than being independent, individual development and broad social-environmental trends are likely to be interrelated, and to develop in response to each other over time.