Humans’ ultra-social lifeways are based on some species-unique social skills and motivations that develop mostly in early childhood. In this talk, I explore two of these: concern for social evaluation and social comparison. First is the way that young children come to self-regulate their actions not just individually, as do many species, but also socially, as they become concerned for how others are evaluating them (especially as cooperators) and adjust their behavior accordingly. Second is the way that young children become concerned not just with how they are treated in absolute terms (e.g., in the division of resources), but how they are treated relative to others. These two sets of social concerns play a critically important role in the way that humans become fully fledged members of a cultural group.