Under interleaving semantic equivalences such as bisimilarity and observation equivalence, concurrency is equated with arbitrary interleaving of actions, so for example, equations such as a | b = ab + ba hold. Recently, a number of non-interleaving equivalences have been proposed in the literature. In this talk, I will describe some of the equivalences that have been defined for labelled transition systems. Examples are location equivalence, loose location equivalence, ST-bisimulation and causal bisimulation. I will discuss approaches to comparing these different equivalences and how this relates to the research I propose to do.