Alcohol is the No. 1 drug of choice on campus, and it's widely available to everyone, including minors. Many students drink heavily and would be considered alcoholics in any other environment. "Soft" drugs like marijuana are also quite prevalent and not hard to find if you know the right kind of people. Students make little attempt to hide these habits and often flaunt them. Thankfully, harder drugs like heroin and cocaine are not in wide use, and most students seem to understand the health risks associated with them.
It's not uncommon to smell weed on your dorm floor despite a ban on smoking, although maybe it's just an honest mistake and the pot smokers didn't understand the administration wasn't just targeting tobacco cigarettes. Probably not, though, as there is a real disregard for the law and lack of respect for fellow students demonstrated by drug users on a continual basis. This being a college campus, peer pressure is a constant, yet passive presence in the lives of most students. Many a high-minded individual starts college looking down on those who waste their time and money on booze, only to be seduced by the fun and debauchery. Honestly, prepare for a sucky, isolated existence if you don't drink at NIU.