Agency is a central concept in the organisational approach to organisms, which accounts for their internal purposiveness. Recent recognition of the active role played by organisms in evolution has led researchers to use this concept in an evolutionary approach. Agency is then considered in terms of ‘unintentional’ choice: agents choose from a given repertoire the behaviour most appropriate to their goal, with this choice influencing evolutionary pathways. This view, while allowing for the evolutionary role of the activity of organisms, presents (...) two pitfalls. First, it restricts organisms’ agency by confining their choice within the bounds of a behavioural repertoire, and assuming their goals are dictated by natural selection. Second, this view, while claiming to eliminate the idea of intentionality, retains its structure: organisms are portrayed as rational entities, persistently pursuing specific goals. This leads us back to a teleological thinking, whose use in evolutionary theory has already been heavily criticised. This paper proposes a conception of biological agency which does not assume goal-directedness but considers agency as inventiveness. An organism will be said to be an agent if it is the triggering cause of behaviours falling outside the known repertoire and whose form can only be explained by the unique relationship between the organism and the environment. If these behaviours have implications in evolution, the agent will be considered an evolutionary agent. The merit of this approach is further validated by evidencing the significant role behavioural innovations play in evolution. Finally, the last section delves into the process of invention by examining animal play. (shrink)