The chapters in this book are based on papers presented at the First Annual Conference of Pattern Languages of Programming (PLoP) held near Monticello, Illinois, in August of 1994. This book is more than just a compendium of conference papers, however. It represents a broad offering from a new body of literature focusing on patterns and pattern languages. This book constitutes what we expect to be the first in a series of similar edited works on an ever-broadening spectrum of software patterns and pattern languages.