Jozef Maria Laurens Theo "Jo" Cals (July 18, 1914-December 30, 1971) was a Dutch politician. He served as minister of education and was prime minister of the Netherlands for little over a year, from 1965 until 1966, as a member of the Catholic KVP party.

After graduating from thr University of Nijmegen in 1940, he practised law in that same city up until 1950, in the meantime also teaching economics for some time on his old secondary school in Roermond. In 1945 Jo Cals became leader of the Catholic Peoples Party (KVP) in Nijmegen municipal council and three years later was elected to the Lower House of Parliament. From 15 March 1950 to 2 September 1952 he was State Secretary for Education, Arts and Sciences in the first and second Drees administrations. For the next eleven years he was Minister of Education, Arts and Sciences in the third and fourth Drees administrations, the second Beel administration and the De Quay administration. As minister of education he helped pass the "Mammoetwet", a law that transformed secundary education. In the debate, he spoke for 6 hours and 50 minutes, setting a record. The cabinet he had formed in 1965 fell as the result of a crisis, known as the 'Night of Schmelzer'.

Cals was born in Roermond, and died in The Hague.