Early onset periodontitis (EOP) which affects individuals thirty-five and younger is characterized by a rapid rate of bone loss and disease progression with defects in host response and a specific etiological microbial flora. Within this classification, there are three subsets of the disease: prepubertal periodontitis, juvenile periodontitis, and rapidly progressive periodontitis. The characteristics of each disease are described along with illustrative cases that will help clinicians diagnose EOP in their patients. Currently prescribed treatment modalities and guidelines from the literature are also discussed in this paper. EOP may represent a complex set of diseases that are likely to be reclassified as further advances in microbiological and genetic research are made. Clinicians should be aware of such changes in order to diagnose, treat, and refer their patients for comprehensive care.