Moral self-concept (MSC) is an important aspect of human morality and emerges in early childhood. It indicates how early children view themselves as moral agents. Yet, its structure and developmental patterns are unclear and require more research. This study addresses if the multidimensional structure of MSC is stable during early childhood and if the dimensions are differentiating over early to middle childhood. We explored the structure of MSC by testing a three-dimensional CFA model, its longitudinal invariance, reliability and correlational structure. Using a three-wave longitudinal sample (N = 133) of children aged between four to six years at T1, we found evidence for a stable three-dimensional MSC model, including the dimensions helping, sharing and comforting.