One of the most important aspects of the research on agent interaction is the definition of agent communication languages (ACLs), and the specification of a proper formal semantics of such languages is a crucial prerequisite for the usefulness and acceptance of artificial agency. Nevertheless, those ACLs which are still mostly used, especially the standard FIPA-ACL, have a communication act semantics in terms of the participating agents' mental attitudes (viz. beliefs and intentions), which are in general undeterminable from an external point of view due to agent autonomy. In contrast, semantics of ACLs based on commitments are fully verifiable, but not sufficiently formalized and understood yet. In order to overcome this situation, we propose a FIPA-ACL semantics which is fully verifiable, fully formalized, lean and easily applicable. It is based on social attitudes represented using a logic of grounding in straightforward extension of the BDI agent model.