Studies into the way parents mediate their children’s (digital) media use are challenging. A reason for this is that parents are not always aware of what they do and why, as their choices do not necessarily involve rational decision-making. In the present study we adopted the notion of “tacit knowledge” (Nonaka & Takeuchi, 1995; Polanyi, 1966) to explore how and why parents of young children mediate digital media use. In-depth interviews were conducted with 24 Dutch parents from 15 families who were selected to represent a range of socioeconomic backgrounds and different family compositions. Through qualitative analysis we first distinguished three mediation styles of “regulation”, “guidance” and “space”. Furthermore, we revealed seven values that drive parental mediation: three core values of “balance”, “freedom” and “protection” that are foundational in the sense that they explain why parents mediate; three orientational values of “qualification”, “Bildung” and “health/fitness” that explain to which end parents mediate; and one additional value of “flexibility” that accounts for parents’ exception-making. Finally, we showed that the most important emotions associated with these values were anger and disapproval (with balance and protection) and love and joy (with orientational values); fear was mentioned occasionally (in relation to protection).