ABSTRACT We focus on children's conscience, an inner guiding system responsible for the gradual emergence and maintenance of self-regulation. Drawing from our research program that has encompassed three large longitudinal studies cumulatively covering the first 6 years of life, we discuss two major components of conscience: moral emotions (guilt, discomfort following transgressions) and moral conduct compatible with rules and standards. We discuss the organization of young children's conscience, focusing on relations between moral emotions and moral conduct, and the development of conscience, focusing on its early form: the child's eager, willing stance toward parental socialization. We also review research on two major sets of influences that predict individual differences in moral emotions and moral conduct: biologically based temperament and socialization in the family. We discuss two inhibitory systems of temperament—fearfulness and effortful control—and several features of socialization, including the style of parental discipline and the quality of the parent-child relationship. Early conscience is an important early personality system, coherently organized, relatively stable over time, and subject to individual differences that emerge as a result of a complex interplay between children's temperamental individuality and socialization in the family.