Covalent bonds between sulfur atoms exhibit lower bond dissociation energy than those between atoms of the second period, bonds that current commodity polymers are typically constructed of. Hereby such -S-S-bond containing polymers address current sustainability challenges plastics face as they can exhibit enhanced degradability as well as chemical and mechanical recyclability. Furthermore, the reversible opening and closing of the sulfur-sulfur bond introduces the potential for self-healing or stimuli responsive behaviour while the electronic nature of the sulfur centres bestow these materials with unique properties such as the ability for transition metal coordination and increased refractive indices. The controlled incorporation of sulfur-sulfur moieties remains however challenging particularly when it comes to linear polymers and often involves the employment of synthetically non-trivial building blocks that require elaborate synthesis. In this regard elemental Sulfur (S8) represents a promising starting material as the desired -S-S-bonds are already preformed. Utilization is furthermore attractive as S8 constitutes a major scale waste product of the petrochemical industry which is produced as part of the desulfuration process of crude oil. As S8 cannot be polymerised by itself into thermodynamically stable macromolecules, many recent efforts have focused on developing copolymerisation strategies forming polymers with oligosulfur Sx links. Typically, this relies on thermally activated radical pathways enabling copolymerisation with (multifunctional) alkenes via so called inverse vulcanisation giving access to a wide range of crosslinked materials. In contrast the synthesis of linear chains from S8 in a controlled fashion is more challenging in particular regarding chains exceeding the oligomer regime. In this context the anionic copolymerisation of sulfur relies on the formation of thiolate intermediates that then achieve S8 ring opening. Unfortunately, although this mechanistic necessity enables copolymerisation of expensive sulfurated heterocycles, it excludes many commonly applied oxygenated comonomers generating alkoxide intermediates upon insertion. Here epoxides would not only be attractive comonomers due to the industrial relevance of propylene oxide but also because of the commercial availability of many others that potentially allows for a facile tuning of the material properties. In this regard we recently found that thiolate intermediates can also be formed during the copolymerisation of CS2 with epoxides and thereby enable incorporation of S8 and effectively make epoxides compatible monomers for elemental sulfur. The ring-opening terpolymerisation (ROTERP) derives from anionic ring-opening copolymerisation (ROCOP) in which two monomers are combined in a strictly alternating fashion and sulfurated variants have recently been in increased focus due to property and chemical recyclability benefits of sulfur containing polymers. In ROTERP however three rather than two monomers are terpolymerised in a sequence selective fashion and the reason how and when to achieve this recently developed concept are largely unanswered. Unfortunately, though the S8 ROTERP depended on an excess of highly toxic carbon disulfide, exhibited limited epoxide scope and produced thionocarbonate -O-(C=S)-O-links which have poor thermal stability decomposing into carbonyl sulfide. This hindered processing and hence any applications as well as other controlled utilisation of the -S-S-bond. Addressing these problems, we here report the incorporation of elemental sulfur into polyesters (Figure ) via ROTERP with epoxides and thioanhydrides.