This volume discusses the evidence for – and implications of – the existence of shared representations in the human brain. When we perceive another person’s actions, emotional states or even tactile sensations, we activate the same motor programs, emotional circuitry and somatosensory networks that would be active if we were to perform those actions, or feel those emotions or sensations. Thus our own representation of an action, emotion or sensation becomes ‘shared’: activated not only by our own action, emotion or touch, but also by the perception of the same events in other people. There is now extensive evidence, discussed in earlier chapters, for the presence of such ‘shared representations’; in contrast, what this chapter addresses is how the brain acquires these shared representations. In this chapter, I focus on shared representations of action, as instantiated by mirror neurons. This is because historically it is shared action representations that have been subject to the most investigation; however, I will conclude with some thoughts on how this work may generalize to other types of shared representation.