Pathogenic germline DICER1 variants cause a hereditary cancer predisposition syndrome with a variety of manifestations. In addition to conferring increased cancer risks for pleuropulmonary blastoma (PPB) and ovarian sex cord–stromal tumors, particularly Sertoli–Leydig cell tumor, individuals with pathogenic germline DICER1 variants may also develop lung cysts, cystic nephroma, renal sarcoma and Wilms tumor, nodular hyperplasia of the thyroid, nasal chondromesenchymal hamartoma, ciliary body medulloepithelioma, genitourinary embryonal rhabdomyosarcoma, and brain tumors including pineoblastoma and pituitary blastoma. In May 2016, the International PPB Registry convened the inaugural International DICER1 Symposium to develop consensus testing and surveillance and treatment recommendations. Attendees from North America, Europe, and Russia provided expert representation from the disciplines of pediatric oncology, endocrinology, genetics, genetic counseling, radiology, pediatric surgery, pathology, and clinical research. Recommendations are provided for genetic testing; prenatal management; and surveillance for DICER1 -associated pulmonary, renal, gynecologic, thyroid, ophthalmologic, otolaryngologic, and central nervous system tumors and gastrointestinal polyps. Risk for most DICER1 -associated neoplasms is highest in early childhood and decreases in adulthood. Individual and caregiver education and judicious imaging-based surveillance are the primary recommended approaches. These testing and surveillance recommendations reflect a consensus of expert opinion and current literature. As DICER1 research expands, guidelines for screening and treatment will continue to be updated. Clin Cancer Res; 24(10); 2251–61. ©2018 AACR .