In 1993, the General Assembly of the United Nations decided that 15 May of every year should be observed as The International Day of Families. This day provides an opportunity to promote awareness of issues relating to families and to increase the knowledge of the social, economic and demographic processes affecting families.

Every year the United Nations provides resources and events that focus on families and their places and the processes that effect them.

Go here for more information:
http://www.un.org/en/events/familyday/index.shtml