Replication and consistency are essential features of any distributed system and have been studied extensively, however a systematic comparison is lacking. Therefore, we developed the Action-Constraint Framework, which captures both the semantics of replicated data and the behaviour of a replication algorithm. It enables us to decompose the problem of ensuring consistency into three simpler, easily understandable subproblems. As the sub-problems are largely orthogonal, sub-solutions can be mixed and matched. Our unified framework enables a systematic exploration of pessimistic vs. optimistic protocols, full vs. partial replication, strong vs. weak consistency, etc.