This article develops the concept of the "parental milieu" as a theoretical tool for biosocial research in environmental education and the emerging field of critical life studies. Using the concept of milieu as a catalyst for theoretical inquiry, we map several movements and variations of the term through the 20th century works of von Uexkull, Simondon, and Deleuze and Guattari. This results in the development of four propositions that connect the parental milieu with the territorial milieu of the animal world; the technical milieu of ubiquitous digital networks; the metabolic milieu of consumption; and the trans-qualitative milieu of fluid relations and queer kinships. We conclude with a call for transgenerational research that addresses the ways that the parental milieu intersects with children's environmental learning and ­ethico-aesthetic sensibilities.