Lymphadenopathy (LAD) is a common presentation in the pediatric population. Cervical LAD with neck mass is the most common manifestation [1]. The etiology of LAD is diverse, including various benign nonspecific reactive conditions, infections, neoplasms, and immune disorders, among others. In spite of the initial concern of lymphoma or infectious conditions, most cases of LAD turn out to be benign and nonspecific reactive. The morphologic features of nonspecific reactive LAD can overlap with those of specific infective LAD or lymphoma. Although some features are more associated with certain etiologies, they are not pathognomonic. Clinical correlation would be essential on this ground. The goal of this chapter is to use case-based illustration to thoroughly demonstrate the morphological features of reactive lymph node and specific entities of non-neoplastic/noninfective LAD.