I'm teaching two sections of a Literature Survey course this semester. It is crucial for the success of this course that students read the assigned texts before coming to class. Unless everybody has done the readings, there will be no class discussions, which, of course, will render the entire course utterly useless.
I have discovered a way to make sure that everybody does the readings. It's very simple. I assign written homework which consists of answering very specific questions about the readings for each day of class. This means that I have 42 homeworks to grade twice a week, which is a huge pain in the neck. However, not a single time this semester have I had to deal with a group of students that hasn't read the text and can't participate in a discussion.
We can complain that the students don't work as hard as we'd like until the cows come home. (This post at College Misery is an example of such useless whining.) The truth, however, is that often the professors themselves are resistant to doing anything to ensure that the students do their homework. Especially, if it implies more work for the professor.