Previous research about parents’ mediation of their young children’s (digital) media use has predominantly focused on the different types, determinants, and effectiveness of parental mediation strategies. Although research on parents’ perceived mediation concerns and competences is scarce, it is known that, compared to mothers and high-educated parents, fathers and low-educated parents experience greater insecurity (i.e., higher concern and lower competence) when applying media mediation. Based on Bourdieu’s theory of social capital it may be expected that—in addition to educational level—marital status and family income predict parents’ perceived mediation concerns and competences: Family demographics may predict parents’ media proficiency and adoption of new media technologies and these media ecological factors may, in turn, affect perceived concerns and competences. To test this assumption, survey data were collected among 1029 parents of children between the ages of 1 to 9 years. We found that parents’ basic media proficiency was lower in low income, low educated, and single-parent families, whereas parents’ advanced media proficiency was only lower in low educated and single-parent families. As expected, parents’ ease of active co-use was positively associated with parents’ basic proficiency, ease of restrictive mediation by basic and advanced proficiency, and ease of imposing technical restrictions by advanced media proficiency. Parents’ perceived mediation concerns were, however, unrelated to parents’ media proficiency. Also, as expected, low educated parents were less inclined to adopt new media technologies. Adoption of new media was negatively related to perceived mediation concerns, yet did not predict parents’ perceived competence.