Risk assessment for periodontal disease must be part of every comprehensive dental evaluation and should include an accurate, current and comprehensive periodontal evaluation. In 2017, the World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions developed a new protocol to classify periodontal diseases. The severity of periodontitis is no longer described as slight, moderate, or severe, but is now categorized by its “stage.” This Quality Resource Guide (QRG) provides an overview of these stages and discusses the criteria assessed, and the effectiveness of the treatment plan based on the identified risks. The QRG will assist the dentist and his/her clinical team, in decision-making and answering patient questions regarding their periodontal status.