Mastery motivation has been identified as key factor for future child competence in early childhood. Whether the development of children's mastery motivation is changeable or stable from toddlerhood to preschool age remains inconclusive. Thus, the purpose of this study was to discuss the previous findings of mastery motivation development and provide the insight into the future early childhood education program and research direction in young children with and without delays. We found that developmental trajectory of mastery motivation on each three domains might vary depending on the child’s phase of development. The developmental trends of mastery motivation differ between young children with and without delays. It is important to recognize that the trajectory of mastery motivation may vary depending on the specific domain. Therefore, early childhood educators should identify each child's strengths and weaknesses to promote and sustain their motivation to participate in daily tasks that are at least moderately challenging for them.