Outside of Hawaii, Trask has worked with the United Nations to aid indigenous people from around the world seeking independence. She was a member of the Indigenous Initiative for Peace, helped author the United Nations Declaration on the Rights of Indigenous Peoples and was elected vice chair of the General Assembly of Nations of the Unrepresented Nations and Peoples Organization. For seven years, she worked and studied under the guidance of Mother Teresa of Calcutta. She is the younger sister of activist and writer, Professor Haunani-Kay Trask. Mililani graduated Kamehameha School in 1969.