Adulthood is a complex social and cultural phenomenon. Although socially obvious, it is fluid in terms of its determinants and the time at which it occurs. The article attempts to answer the question what is it that emerging adults grow up to, and what is the goal of the process of growing up? The guiding objective was therefore to reconstruct a grounded theory of adulthood. For this purpose that qualitative research embracing semi-structured interviews was designed and carried out. The findings are locally embedded and aim to reconstruct the concept of adulthood prevailing in contemporary Polish culture, built on the experiences and opinions of Poles of different ages. The social construct of adulthood that emerges from our research constitutes the sum of economic independence, responsibility for oneself and for others, and emotional self-control. These features are also the opposite of the stereotypical image of childhood, as a time of dependence, carefreeness, and vulnerability. This means that growing up in our culture is a long-lasting process of transition between two extremes, but a process that only prepares one to a small degree for such a revolution in one’s life, and this has its psychological and social consequences.