James is 14 years old. Tall, handsome, funny, athletic, attuned to others, he is one of the popular, high-status students in his large freshman class. He can also be remarkably caring and attentive with his close friends. But James has a dark side. Sometimes he uses his social skills to manipulate others, and he draws a bright line between those…

Peer influence and social interactions can give rise to spillover effects in which the exposure of one individual may affect outcomes of other individuals. Even if the intervention under study occurs at the group or cluster level as in group-randomized trials, spillover effects can occur when the mediator of interest is measured at a lower level…

Schools are an important context for children's social and emotional development. In classrooms and other school settings, children and adolescents need to have skills such as managing negative emotions, being calm and focused, following directions, and navigating relationships with peers and adults. To build and support these skills, schools have…