This study investigated the short-term effects of behavioural training for preschool children. The goals of this programme were to reduce disruptive behaviour as well as shy and withdrawn behaviour, and to promote social-emotional competencies. In young children, insufficient emotional competencies and difficulties concerning adequate conflict resolution are already related to conduct disorders and problems with peers. At the same time, preschool age is a developmental stage where children begin to acquire many social-emotional competencies. Method: The study used a quasi-experimental evaluation design with eight preschool classes of children (N = 90) aged three to six years. In order to assess the impact of the social-emotional skills training, intervention and control group outcomes were to be compared pre- and post-test. The effects on behaviour problems and social-emotional competencies were assessed by teacher ratings. Results: Relative to controls, children displayed fewer problems with peers as well as less restless, inattentive behaviour and their emotion regulation skills and academic skills had improved. However, no effects were found regarding aggressive behaviour or emotional problems. (Contains 2 tables and 1 figure.)