The feeling that our body belongs to us, and that it is an essential part of ourselves, is a fundamental aspect of human self-awareness and individual psychological identity. The intimate relation between the sense of body ownership and the sense of self emphasizes the importance of understanding the former in order to access and comprehend the latter. However, it also outlines the challenge of objectifying the body by turning it into a subject of controlled experimental research. This dissertation describes a series of scientific studies in which an experimental method of 'body swapping' was developed with which to overcome this immanent hindrance and study for the first time the mechanisms underlying the feeling of an entire body as belonging to oneself. The results of the studies presented here indicate that it is possible to induce healthy participants to experience the body of a shop mannequin or the body of another individual as their own body. Neuroimaging data link the unitary experience of owning an entire body with activity in neuronal populations that integrate multisensory information across body segments in body-centered reference frames.