The chapter has two main goals. The first is to study what rules are grounded on. Regularities and related philosophical topics can be understood in many ways and at many levels, such as (simple) regularity, rule as law-like, rule-following, and rule-conforming. Sellars’s rule-governed behaviour is central. According to it, acts are done because of a rule, but not because of an awareness of a rule. This enables us to avoid regress in language-learning and getting bogged down in rule-following.The second main goal is to study why rules are binding – that is, on what their normativity is founded. It will be argued that the community must stipulate rules or at least acknowledge them implicitly in practice amid a sea of regularities. This acknowledgement, or normative attitude, forms a standard for correct and incorrect acts. This opens yet another topic to be examined: Can our judgments be right or wrong in some more substantial way that goes beyond communal assent? Is there something like ‘genuine normativity’ in a community-transcending sense? I shall answer this in the negative. The conclusion is that belonging to a community and the choice between them is central to normativity.