Jozef Maria Laurens Theo "Jo" Cals (July 18, 1914 – December 30, 1971) was a Dutch politician of the defunct Catholic People's Party (KVP) now merged into the Christian Democratic Appeal (CDA). He served as Prime Minister of the Netherlands from April 14, 1965 until November 22, 1966.
He previously served as a Member of the House of Representatives from August 19, 1948 until March 15, 1950, when he became State Secretary for Education, Culture and Science serving from March 15, 1950 until September 2, 1952 in the Cabinets Drees-Van Schaik and Drees I. He became Minister of Education, Culture and Science serving from September 2, 1952 until July 24, 1963 in the Cabinets Drees II, III, Beel II and De Quay. He again returned to the House of Representatives for two short periods, after the Dutch general election of 1956 and 1959. Serving from July 3, 1956 until October 3, 1956 and from March 20, 1959 until May 19, 1959. And again a Member of the House of Representatives from July 2, 1963 until April 14, 1965. After the fall of the Cabinet Marijnen, Cals became Prime Minister of the Netherlands, leading the Cabinet Cals.
After his premiership, Cals semi-retired from active politics and served as a civil servant leading several governmental commissions. On December 5, 1966 he was granted the honorary title of Minister of State, which he held until his death.