This thesis deals with the implementation of religious education in the institutions for early and preschool education in Zadar County. The preschool institution is of essential importance for whole child development. The religious atmosphere in the family as well as in the institutions in which the child spends his/her time is the basis for his/her spiritual life. Modern programmes implemented in the institutions for early and preschool education are based on the principles of humanistic development including pluralistic tendency towards affirmation of diversity within the preschool programme. Entire programmes aim at the encouragement and development of all existent and potential competencies of the child; however, equally important are the specialised interest programmes which should encourage the development of the child's abilities, such as the religious education programme. Therefore, this thesis deals with religious education, its characteristics and influence on whole child development. Also, it focuses on religiousness and presents Christian, i.e. Catholic education as the mostly implemented religious programme not only in Zadar County but also in Republic of Croatia. This thesis shows the historical development of the implementation of Catholic education in the institutions for early and preschool education as well as the characteristics of the religious Catholic programme in Republic of Croatia. The section on the conducted research shows the results which have been obtained in the survey. Its aim was to check whether religious education programmes have been implemented in the institutions for early and preschool education in Zadar County as well as to check whether preschool teachers have additional education for the implementation of the programme. In addition, it also included the preschool teachers’ evaluation of the influence of religious education on whole child development.