Chemical activity (science, research, engineering, innovation) – through its entanglement with technological development – affects and impacts normative and other value-related discourses concerning social and environmental dimensions of science and technology (S&T) progress. It is now time to introduce the concept of responsibility in order to clarify the position of chemists in this discourse. Many responsibility attributions, especially from the public, apparently, are not justified and are mere accusations. Others are justified but chemists might not be aware of them. The difference is often one of a conceptual dimension: who can be held responsible by whom, for what exactly, and in view of what rules, competences and knowledge? Apparently, responsibility attributions are only legitimate when the agent that is held responsible has the cognitive capability to understand and act in accordance with certain expectations and obligations. Moreover, different types of responsibility need to be differentiated in order to make justified claims: legal, social, political, organisational, and moral responsibilities. The considerations in this chapter, basically, have two goals. First, it will help chemical practitioners defining their roles in progress and public discourse. This implies acceptance of some responsibility ascriptions and refutation of others. In any case, plausible arguments are required to claim or reject responsibilities. This chapter will provide such a line of argumentation. Second, it will convince chemists that their most general responsibility – contributing with their expertise and competence to the collective endeavour of sustainable S&T progress – arises from an obligation to serve the common good.