Twenty-five years have elapsed since the first publication of this book. The growth of basic knowledge since then has been both enormous and momentous. This has been a joyous enterprise for us. Our ability to treat acne and rosacea ef­ fectively has outpaced the vastly expanded understanding of their etiologies. Acne today is not only an eminently treatable disease; in some cases, for exam­ is actually curable. We think that no case is so severe as to pIe acne conglobata, it be beyond help with the array of diverse drugs now available. Treatment failure is really physician failure. Prevention of acne in high-risk children has also be­ come a promising possibility, now that it is possible to identify small comedones in prepuberty, as early as the age of 7 years. Topical comedolytic agents such as retinoids prescribed at the incipient stage might then prevent the evolution of the full-fledged disorder. This therapeutic maneuver could prevent the dreaded sequel of scarring. We adhere firmly to the beliefs expressed in 1975 regarding our mission. This text is dedicated to the dermatologists and other practitioners who must diagnose and treat these disfiguring, remarkably protean, common disorders.