 He was a regular contributor to "The Times", "L-Orizzont" and "Malta Today" before serving as editor of "Illum" between 2008 and 2010.Vassallo first joined the Green movement, a now defunct group, in 1979.In 1981 he became a member of "Żgħażagħ għall-Ambjent", one of the first Maltese environmentalist movements, which was later to rename itself to "Moviment għall-Ambjent" and, eventually, Friends of the Earth (Malta).