Decades of research has assessed the benefits of children's and adolescents' friendships, but friendships among youth often dissolve within a matter of months or years. Studies have investigated predictors and consequences of friendship stability with the expectation that, in order for friendships to have a positive or negative influence on youth,…

In this article, we test an alternative approach to creating a counterfactual basis for estimating individual and average treatment effects. Instead of using control/comparison groups or before-measures, the so-called Counterfactual as Self-Estimated by Program Participants (CSEPP) relies on program participants' self-estimations of their own…