In 1961, Fenech Adami became involved with the Nationalist Party (PN) and was assistant general secretary from 1962 to 1975. By the age of 43, he had become the leader of the PN. In 1979, he became the vice president of the European Union of Christian Democrats. He took the seat of a deceased PN Member of Parliament (MP) in 1969 and was first elected on his own in 1971. He was the PN's spokesman for Labor and Social Services between 1971 and 1977. Serving in Parliament as the leader of opposition from 1983 to 1987, he rallied support for his appointment as prime minister in 1987 and again in 1998.