Like every college campus in America, Caltech has some drug use. Drugs certainly are not an integral part of Caltech culture, though. There are students who drink, smoke pot, and the like, but there is no peer pressure to try drugs, and people don't walk around offering them to others. There is a large constituency of students who have never had a drink before, more so than at other non-religious colleges. Alcohol is the most common substance on campus. There is probably some underage drinking, but less than at most other colleges. A lot of the students here abide by the laws and do not drink until they are over 21. If there is a certain drug a student is looking for, the student will most likely be able to find it. However, the student has to make an active effort; narcotics will not present themselves at every corner or at any school research labs.
Alcohol is used by many Caltech students, but not on a daily basis. Some students have specific drinking nights or parties when their main objective is alcohol consumption, but most students who drink are social drinkers. When there are parties or "happy hours," they are checked by the school, and bartenders who card are hired to dispense alcohol to those who are of age. The school is pretty strict about what they will allow students to do on campus. Cigarettes are used by a fair number of students at the school, but no more than about five percent of students smoke on a regular basis. Overall, Caltech is a clean campus when it comes to drugs.