Behavior analytic research on rule-governed behavior was first gathered in this book in 1989. Shortly after that time, the area slowed, perhaps in part due to the difficulties in distinguishing verbal from non-verbal processes within behavior analysis. Recently, however, there has been a notable pick up in interest in the topic. This previously out-of-print volume has been reprinted by Context Press in order to provide a readily accessible resource to behavioral psychologists as they move ahead in their research and practical work.