We recommend...
From the airport: take the metro line 8 to Nuevos Ministerios. Change there to the commuter train line (Cercanías), and take the train in the direction of Parla (C4). Get off at the stop Las Margaritas/ Universidad. Upon leaving the train station from the main exit, turn right and walk straight ahead for 5 minutes or so until you reach the University campus.
WE RECOMMEND THAT YOU DO NOT TAKE THE METRO TO UC3M.
From the AVE:take the Parla train (line C4) in Atocha station and get off at the stop Las Margaritas/ Universidad. Upon leaving the train station from the main exit, turn right and walk straight on for 5 minutes or so until you reach the University campus.
From the centre of Madrid: the quickest way is to take the metro line 1 to Atocha Renfe station and then take the commuter train (Cercanias) in the direction of Parla (C4) Get off at the stop Las Margaritas/Universidad. Upon leaving the train station from the main exit, turn right and walk straight on for 5 minutes or so until you reach the University campus.