Although the ever-growing Islamist movement under Imam Khomeini played a key role in the formation and final victory of the Islamic Revolution during 1978-1979, the Islamic Revolution was also assisted – however less sensible - by the influence and participation of three political currents known as the National Liberal spectrum, the Leftwing or Leftists and Eclectic ideology. After the Revolution, Tudeh Party of Iran, as the most influential Leftist political organization, tried to gain political power and social prestige although its role in the revolutionary developments was not outstanding. This paper intends to study the policies and approaches of Tudeh Party of Iran from the establishment of the Islamic Revolution to the constitutional referendum (April 1, 1979 through Dec. 3, 1979) toward the newly established Islamic Republic and the rival political currents for promoting and consolidation of its position in political and social arena of the country.The research method called for historical review of the subject under study through process tracing. Findings of the research work indicate that Tudeh Party of Iran had opportunistically tried to display an approach toward revolutionary causes and goals, relatively similar to the Islamist current under Imam Khomeini, through highlighting and accentuating Islamic Revolution and Islamic Republic’s anti-imperialistic doctrine. At the same time, the party maintained an opposing and even hostile position against the National Liberal current and other Leftist parties and political groups who favored – unlike Tudeh Party – an anti-Soviet Union tendency claiming their ideology was incompatible with that of the Islamic Revolution.