In this theoretical paper, selected areas of moral development as well as some of the respective theories and models are used to characterise positive, healthy moral development. Such moral development is seen as one prerequisite of nonkilling. From a lifespan perspective, core concepts such as moral motivation and moral agency are combined into an understanding of moral development, as based on the making meaning of experience in the context of social interaction and co-construction. The aim of (socio)moral development is seen in moral maturity, that is, the genuine understanding of the way our own actions or nonactions affect the welfare of others, including the motivation, the sense of personal responsibility, and the will to act in such ways as not to harm or to protect or re-establish others' welfare. Reaching this aim can be seen as the outcome of healthy moral development.