Pieter "Piet" Lieftinck (30 September 1902 – 9 July 1989) was a Dutch politician of the Christian Historical Union (CHU) party and later the Labour Party (PvdA) and economist.
Lieftinck applied at the Utrecht University in June 1919 majoring in Law and Economics and obtaining Bachelor of Economics and Bachelor of Laws degrees in July 1922 and worked as a student researcher before graduating with a Master of Economics and Master of Laws degree's in October 1927. Lieftinck served in the Royal Netherlands Army as a lieutenant from November 1927 until November 1928. Lieftinck applied at the Columbia University in New York City in April 1929 for a postgraduate education and obtained a Master of Financial Economics degree in December 1930 and later returned to the Utrecht University where worked as a researcher and got a doctorate as an Doctor of Philosophy in Public economics on 10 December 1931. Lieftinck worked as civil servant for the Ministry of Labour, Commerce and Industry from Augus