In the past two decades, psychologists, educators, and economists have shown that social stratification creates social inequalities that have long-term detrimental effects on children's physical, emotional, and academic development. The segregation of social networks, as well as experiences of social inequality in the form of prejudice and bias, contributes to negative developmental outcomes for children over and above unequal access to material resources. Unfortunately, hate and bias crimes have increased significantly over the past decade, turning the clock back on progress toward just and fair treatment of individuals. According to the Southern Poverty Law Center, K-12 schools are the most cited locations for discrimination and bias-related harassment. Most commonly, children discriminate against and harass other children because of their race/ethnicity, gender, immigration status, or religion. These reports are consistent with extensive developmental research that has shown that children are both the recipients and perpetrators of prejudicial attitudes. The author, a researcher of children's social and moral development explains how teachers can lead discussions about bias and promote intergroup friendships to reduce prejudice.