The current clinical descriptive terminology used to describe increase in size of the gingiva is gingival enlargement and gingival overgrowth. This chapter covers the classification of gingival enlargement, inflammatory enlargement, noninflammatory gingival enlargement, enlargement associated with systemic diseases or conditions, neoplastic enlargement (gingival tumor), and false enlargement. Gingival enlargement are classified as according to etiological factors and pathologic changes, according to location and distribution, syndromes associated with diffuse gingival enlargement, and new clinical index for drug-induced gingival overgrowth. Inflammatory enlargement can be of two types following as acute inflammatory enlargement and chronic inflammatory enlargement. False enlargements are not true enlargements of gingival tissues, but may appear as a result of increase in size of the underlying osseous or dental tissues.