Learning is a crucial component of adaptive behaviour on many levels. At the simplest end of the spectrum, it permits agents to learn associations between stimuli or events to navigate in the world and form appropriate responses, e.g. through reflexes in classical conditioning. Together with increasing complexity, agents learn how the world changes in response to their behaviour, and to engage that behaviour instrumentally in pursuit of rewards. The extent to which consciousness is required for different forms of learning is essential to understanding its function and role. Yet, empirical evidence has been inconclusive and riddled with methodological issues. In this talk, we present evidence for and against unconscious learning at increasing levels of complexity, from associative learning, to classical fear conditioning, to different versions of instrumental conditioning. This series of studies suggests that conscious access might be essential for learning and engaging instrumental behaviour, but less critical for learning simple associations. Crucially, maintaining the methodology as similar as possible allows to determine the boundary conditions for learning without consciousness. We discuss the implications for adaptive behaviour both in human and non-human animals, and the implications for the function of consciousness.