Quō vādis? (Classical Latin: [kʷoː ˈwaːdɪs], Ecclesiastical Latin: [kwo ˈvadis]) is a Latin phrase meaning "Where are you marching?". It is also commonly translated as "Where are you going?" or, poetically, "Whither goest thou?"

The phrase originates from the Christian tradition regarding Saint Peter's first words to the risen Christ during their encounter along the Appian Way. According to the apocryphal Acts of Peter (Vercelli Acts XXXV; late 2nd century AD), as Peter flees from crucifixion in Rome at the hands of the government, and along the road outside the city, he meets the risen Jesus. In the Latin translation, Peter asks Jesus, "Quō vādis?" He replies, "Rōmam eō iterum crucifīgī" ("I am going to Rome to be crucified again"). Peter then gains the courage to continue his ministry and returns to the city, where he is martyred by being crucified upside-down. The Church of Domine Quo Vadis in Rome is built where the meeting between Peter and Jesus traditionally took place. The words "quo vadis" as a question also occur at least seven times in the Latin Vulgate.