Appendiceal neoplasms encompass a heterogeneous group of tumors which include both non-epithelial (neuroendocrine neoplasms) and epithelial subtypes. This chapter reviews epithelial appendiceal tumors which include both mucinous and non-mucinous histologies. The American Joint Committee on Cancer Staging Manual (AJCC 8th edition) has the most updated staging criteria and categorization of these tumors. Appendiceal neoplasms exhibit a wide range of clinical presentations, prognoses, and malignant potentials. As a result, treatment of these tumors involves a nuanced understanding of the specific subtypes and requires expertise from clinicians who specialize in the treatment of appendiceal and peritoneal malignancies. Surgery remains the mainstay of treatment for these neoplasms and often involves cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) for patients with peritoneal metastases and pseudomyxoma peritonei (PMP). Chemotherapy may be useful in patients with adenocarcinoma. Close surveillance is warranted in the majority of cases after treatment.