In 1964 a House of assembly with 64 members was formed. Internal self-government came into effect in 1973, followed by full independence on 16 September 1975.
Black, red and yellow are traditional colors which are found in Papua New Guinean art and clothing. The yellow bird, a stylized bird of paradise, is culturally significant to Papua New Guineans and in full flight it represents freedom and the country's birth as an independent nation. The five stars symbolize the constellation the Southern Cross, representing the country's geographical position in the world and its link to Australia, which also incorporates the Southern Cross on its flag.
PNG Flag info from here