Our school publishes a "Code of Rights, Responsibilities, and Conduct" booklet with a section for students, one for teachers, and one for parents. It gets sent home every year and parents have to sign a form saying they received it (and, hopefully, read it). Behavior expectations, consequences, and disciplinary procedures are clearly spelled out.
A lot of the rights are soft and subjective (be respected, be able to appropriately express opinions), but some are quite clear (students can't chew gum, run in the halls, bring walkmen or radios into the school.)
Beyond that, a lot of teachers (at least for the younger grades) spend time early on setting up a list of maybe 5 "good behavior" rules for that classroom. The kids participate in setting up the rules. This year, my son's teacher included points to be added for good behaviors, and points to be subtracted for bad behaviors. She set up a list of rewards based on an accumulation of points.
My son was quite excited the other day. His class reached their first milestone, and the first reward is an outdoor class game. I think the next reward is extra recess, and the highest reward is an ice cream party. What comes after that, who knows? I'm sure my son secretly hopes they'll get an extra-long summer vacation!