The aim of this paper is to study the methods for assembly representation supporting the level of automation (LoA) decision process. Based on a literature review on the topic of LoA decision-making, a need for involving the assembly sequence in the decision was identi?ed. The representation methods used in both assembly modelling and planning and other more generic approaches in the literature were studied and evaluated. The evaluation has been based on a requirements de?nition describing how the representation should support the decision about automation. Identi?ed gaps in requirement satisfaction from the existing approaches led to the de?nition of the assembly sequence modelling language (ASML), a new modelling language that combines principles from and improvements on the studied methods and a standard vocabulary of assembly actions. The modelling language was demonstrated in an assembly example and was successfully evaluated with regard to the de?ned requirements. Thus, this new modelling approach, ASML, is offered as an innovative and intuitive support in the decision-making process for selecting automation levels in Assembly.