Philosophy and psychology have dedicated an important amount of attention to the role that commitments may play in the establishment, motivation and unfolding of joint action. In this paper, we explore how commitments may also be a fundamental element in human-robot joint actions and in the design of socially appropriate robots. After introducing the notion of joint action, we discuss its potential importance for the perception of sociality in robots through two different but complementary philosophical analyses of commitments. Those two analyses emphasize two central aspects of commitments: their capacity for reducing uncertainty and their normative force. Then, we sketch a particular framework of how a robotic architecture for commitment may capture the two aspects and how they can be modelled. Finally, we conclude with some remarks regarding the long-range consequences and considerations of introducing the notion of commitment in the research on social robotics and its role concerning sociality and social appropriateness.