Management of retroperitoneal soft tissue sarcomas (RP STS) can be very challenging. In contrast to the more common extremity STS, the two predominant histologic subtypes encountered in the retroperitoneum are well-differentiated/dedifferentiated liposarcoma and leiomyosarcoma. Surgery remains the mainstay of treatment for RP STS. Preoperative planning and anticipation of the need for resection of adjacent organs/structures are critical. The extent of surgery, including the role of compartmental resection, is still controversial. Radiation therapy may be an important adjunct to surgery to provide locoregional disease control; this is currently being evaluated in the preoperative setting in the EORTC STRASS trial. Systemic therapy, tailored to the specific histologic subtype, may also be of benefit for the management of RP STS. Further investigation of novel therapies (e.g., targeted therapies, immunotherapy) is needed. Overall, multi-institutional collaboration is important moving forward, to continue to better understand and optimize management of this disease.