Simple SummarySoft-tissue sarcomas are exceedingly rare, accounting for <1% of all adult malignancies. Sarcomatous tumors are located within the retroperitoneum in <10% of cases. International collaborations have been instrumental in advancing our understanding of these rare tumors in the last decade. Notably, standard treatment has become upfront primary surgical resection for most subtypes. Radiation and systematic therapy have a limited role. In this 2021 review, we detail the anatomical boundaries of the retroperitoneum, risk factors including genetic predispositions, clinical characteristics, histologic-specific management, contemporary standard of care, recent advancements and limitations of knowledge in the treatment of retroperitoneal sarcoma care. Soft-tissue sarcomas are biologically heterogenous tumors arising from connective tissues with over 100 subtypes. Although sarcomas account for <1% of all adult malignancies, retroperitoneal sarcomas are a distinct subgroup accounting for <10% of all sarcomatous tumors. There have been considerable advancements in the understanding and treatment of retroperitoneal sarcoma in the last decade, with standard treatment consisting of upfront primary surgical resection. The evidence surrounding the addition of radiation therapy remains controversial. There remains no standard with regards to systemic therapy, including immunotherapy. Adjunctive therapy remains largely dictated by expert consensus and preferences at individual centers or participation in clinical trials. In this 2021 review, we detail the anatomical boundaries of the retroperitoneum, clinical characteristics, contemporary standard of care and well as recent advancements in retroperitoneal sarcoma care. Ongoing international collaborations are encouraged to advance our understanding of this complex disease.