The current demand for flexible software development makes software development organizations consider iterative and incremental development approaches as alternatives to the classical waterfall software development model. This, however, may jeopardize process visibility and manageability as well as product quality. Therefore, modern software development organizations need to find ways to install flexible development processes without sacrificing project overview and control. This paper reports experiences from a real life project that used timeboxing as the basic organizing principle in an incremental and iterative design and construction process. The project’s experiences show that such a process is indeed both flexible and manageable but that it requires periodic planning and replanning, explicit concern for coordination and synchronization activities, high process discipline and organizational readiness to accept fluctuating requirements.