"Humans are social creatures throughout life. This proposal aims to advance our knowledge of the mechanisms that mediate understanding of others’ actions from a developmental perspective. A special emphasis will be devoted to mirror neuron and teleological frameworks. The former framework focuses on reciprocal motor activation during action execution and observation whereas the later framework emphasizes the application of abstract principles to observed events. The mechanisms that guide both processes will be investigated in isolation, but special attention will also be devoted to understanding how these diverse forms of action understanding jointly contribute to action understanding. The project encompasses three essential research objectives, illustrated by three research questions. How do mirror neuron and teleological processes influence action understanding? How does action understanding enable social action evaluation (empathy and pro-social preferences)? How is action understanding expressed during real-life social interactions? These questions will be addressed by presenting infants and toddlers with social events of varying complexity (from simple actions and animated sequences to complex everyday social events), relating empirical findings to predictions derived from the teleological and motor cognitive frameworks. The overarching aim is to provide a computational model of early emerging social cognitive capabilities, with a focus on action understanding and action evaluation, while passively observing others and while partaking in social interactions with others."