\u3cp\u3eCompositional model checking approaches attempt to limit state space explosion by iteratively combining behaviour of some of the components in the system and reducing the result modulo an appropriate equivalence relation. For an equivalence relation to be applicable, it should be a congruence for parallel composition where synchronisations between the components may be introduced. An equivalence relation preserving both safety and liveness properties is divergence-preserving branching bisimulation (DPBB). It is generally assumed that DPBB is a congruence for parallel composition, even in the context of synchronisations between components. However, so far, no such results have been published. This work finally proves that this is th...