Two related fields, the psychological and neuropsychological ones, provide an exhaustive overview of the complex issue of agency and self-agency. The cognitive and neuropsychological correlates are here considered as two sides of the same coin, since we have the main scope to find a correspondence between the hardware (cerebral processes) and the software (cognitive processes) of the representation of agency. All living system self-regulates, or, within any living system,there is a need of communication among the different parts of that system. This can include a unit as small as a cell, a plant, or animal, or even a more complex organism. For example, one's systems are regulating one's temperature: regulation is a property of the living system. Secondly, in order to act it is necessary for organisms to be able to distinguish between self and other, whatever this ability is learned or is a part of the process of action. The predominant account on explaining the sense of agency of our actions is the ??central monitoring theory" or ??comparator model" that postulate a monitoring of central and peripheral signals arising as a consequence of the action execution . Moreover, the simulation theory is considered in alternative to the comparator perspective. Secondly, the contribution of body representation for agency is explored, taking into account the significance of proprioceptive feedback for self-agent attribution. Finally, the neural correlates of action and agent representation are considered in the light of new empirical results.