A robotics workcell is by nature a hierarchically distributed system, composed of elements such as robots, machining tools and vision systems, whose actions must be carefully coordinated. The first problem to solve is their integration into a single workcell programming and control environment. Such an environment should provide a flexible way of coordinating the actions of these elements in terms of generic (device-independent) commands which are eventually mapped to the native command languages (if any) of the physical devices. In this paper we describe the programming and control environment WORKPROV with emphasis placed on the distributed and hierarchical run time control of the workcell.