Pediatric fibroblastic and myofibroblastic tumors are a relatively common group of soft-tissue proliferations that are associated with a wide spectrum of clinical behavior. These tumors have been divided into the following categories on the basis of their biologic behavior: benign (eg, myositis ossificans, myofibroma, fibromatosis colli), intermediate-locally aggressive (eg, lipofibromatosis, desmoid fibroma), intermediate-rarely metastasizing (eg, inflammatory myofibroblastic tumors, infantile fibrosarcoma, low-grade myofibroblastic sarcoma), and malignant (eg, fibromyxoid sarcoma, adult fibrosarcoma). Imaging has a key role in the evaluation of lesion origin, extent, and involvement with adjacent structures, and in the treatment management and postresection surveillance of these tumors. The imaging findings of these tumors are often nonspecific. However, certain imaging features, such as low or intermediate signal intensity on T2-weighted magnetic resonance images and extension along fascial planes, support the diagnosis of a fibroblastic or myofibroblastic tumor. In addition, certain tumors have characteristic imaging findings (eg, multiple subcutaneous or intramuscular lesions in infantile myofibromatosis, plaquelike growth pattern of Gardner fibroma, presence of adipose tissue in lipofibromatosis) or characteristic clinical manifestations (eg, great toe malformations in fibrodysplasia ossificans fibroma, neonatal torticollis in fibromatosis colli) that suggest the correct diagnosis. Knowledge of the syndrome associations of some of these tumors-for example, the association between familial adenomatous polyposis syndrome and both Gardner fibroma and desmoid fibromatosis, and that between nevoid basal cell carcinoma syndrome and cardiac fibroma-further facilitate a diagnosis. The recognition of key imaging findings can help guide treatment management and help avoid unnecessary intervention in cases of benign lesions such as myositis ossificans and fibromatosis colli. In this article, we describe the various types of fibroblastic and myofibroblastic tumors in children and the characteristic clinical manifestations, imaging features, and growth patterns of these neoplasms-all of which aid in the appropriate radiologic assessment and management of these lesions. (©)RSNA, 2016.