Abstract Partial closure under weak composition, or partial -consistency for short, is essential for tackling fundamental reasoning problems associated with qualitative constraint networks, such as the satisfi- ability checking problem, and therefore it is crucial to be able to enforce it as fast as possible. To this end, we propose a new algorithm, called PWC? , for efficiently enforcing partial -consistency on qualitative constraint networks, that exploits the notion of abstraction for qualitative constraint networks, utilizes certain properties of partial -consistency, and adapts the functionalities of some state-of-theart algorithms to its design. It is worth noting that, as opposed to a related approach in the recent literature, algorithm PWC? is complete for arbitrary qualitative constraint networks. The evaluation that we conducted with qualitative constraint networks of the Region Connection Calculus against a competing state-of-the-art generic algorithm for enforcing partial -consistency, demonstrates