Metacognition is a crucial prerequisite for self-regulated learning and refers to the knowledge and the regulation of cognitive processes. Several authors argue that children at preschool age can use initial metacognitive control strategies and monitor their learning activities. This fact will create the conditions for promoting metacognitive activities at an early stage. The development of these activities at this age is influenced by several contextual factors, such as home or school environments. Essential caregivers exert a strong influence in terms of the development of metacognitive abilities. In view of this above 137 children participated in an intervention study aiming to improve metacognitive skills, along with their important caregivers such as parents and kindergarten teachers. Training concepts were designed that combined different kinds of interventions: a direct age-appropriate training of the preschoolers and two indirect interventions catered to parents and kindergarten teachers. The aim of this study was to analyze which training condition is more effective in improving metacognitive skills. We assumed that preschoolers who are consistently supported in their self-regulated learning in kindergarten and at home would benefit the most. Based on our data, we could partly confirm this hypothesis.