The surgical treatment of localized soft tissue sarcoma (STS) of the extremity traditionally involves excising the tumor with a surrounding margin of normal tissue to minimize the risk of local recurrence (LR). Although radiation therapy has advanced limb-salvage surgery without compromising local recurrence, metastasis-free survival, and overall survival, the definition of “negative” surgical margins remains inconsistent across different guidelines. This chapter explores various classification systems used to assess surgical margins, including the Enneking, R, UICC, and Toronto Margin Context Classification (TMCC), among others. The impact of margin quality, the role of adjuvant radiation therapy, and the clinical implications of different margin definitions are discussed. Furthermore, the chapter examines the prognostic value of surgical margins in relation to LR and overall survival, highlighting that not all positive margins bear the same risk. In particular, planned close margins along critical structures, as well as margins in infiltrative and myxoid liposarcomas, are critically evaluated. Finally, the chapter calls for evidence-based standardization of margin classification to enhance clinical decision-making and outcome predictability in STS management.