Materials and books are in english but most lectures are given in spanish (as sunnyskies above me stated). I have a friend who attends in ponce and she says this is how it is run...thankfully she happens to be fluent. I know another guy who is there who speaks NOTHING of spanish, so I have no clue how he is winging it. My fluent friend states that some lectures are even given in somewhat informal language (like using puerto rican slang terms for things and structures even, not correct dictionary spanish!), which strikes me as horribly unprofessional, but whatever...I guess you get what you pay for.