Most parents care deeply about their children. If that were enough, we would not see the inequalities we currently do in children's opportunities and healthy development--children out of school, children laboring, children living in poverty. While the scale of the problems can seem overwhelming, history has shown that massive progress is possible on problems that once seemed unsolvable. Within the span of less than twenty-five years, the proportion of people living in extreme poverty has been cut in half, the number of children under age five that die each day has dropped by over 12,000,...