The development of children's cognitive and social skills is a topic of considerable importance and interest in education and educational psychology. The current study examines whether emotion knowledge and self-regulation predict cognitive competence, social competence, and classroom behavior problems among a sample of 74 preschoolers (40 boys). A hierarchical regression was used to control for age, child gender, and family income level before predicting cognitive competence, social competence, and classroom behavior problems from emotion knowledge and self-regulation. Emotion knowledge incrementally predicted both cognitive competence ([Delta]R[superscript 2] = 0.06) and social competence ([Delta]R[superscript 2] = 0.08) but not classroom behavior problems. Conversely, self-regulation predicted classroom behavior problems ([Delta]R[superscript 2] = 0.07) but not cognitive or social competence. In addition, results demonstrated that the situation knowledge (not the expression knowledge) component of emotion knowledge was the active ingredient for both cognitive and social competence. However, different aspects of self-regulation were relevant for different outcomes: The attentional control element was important for cognitive competence, whereas the positive emotionality element was important for social competence and behavior problems. The study demonstrates that emotion-related competencies are important prerequisites for valued educational and social outcomes in preschoolers. (Contains 2 tables and 1 figure.)