The main aim of this thesis was to examine the relationship between parental emotion-related socialization behaviors (ERSBs), children’s emotion understanding and externalizing behavior problems in two Norwegian samples of kindergarten children and their parents. This thesis consists of three papers. In paper I we found that parental ERSBs were significant predictors of externalizing behavior problems. Paternal non-supportive ERSBs comprised a particularly strong predictor and interacted with maternal ERSBs. In paper II we found that parental non-supportive ERSBs (distress reactions) predicted externalizing behavior problems. In addition, we found evidence of an indirect pathway from supportive ERSBs (parental expressive encouragement) to externalizing behavior problems via children’s emotion understanding. In paper III we found that the TIK program led to an increase in expressive encouragement, which positively predicted emotion understanding in children at baseline and follow-up. An important contribution of this thesis is that it is the first study to replicate previous findings on emotion socialization in a Nordic cultural context.