The Concise Edition is a stream-lined version for a four unit course. It omits note materials and cases and a few principal cases that are included in the longer version to under-score or elaborate upon the key principles in each unit.

The Ninth Edition continues the approach of earlier editions in emphasizing rich, full-bodied versions of the principal cases, a functionalist approach to the problems of contract law, and analytical notes on such issues as the differences between classical and modern contract law and the role of the limits of cognition in contract law.

The new edition includes a great number of new principal cases, including extensive coverage of pertinent materials in the new restatement of restitution and up to date materials on "rolling contracts".