The USES-groupat the Universität des Saarlandes follows an approach to compute reliable run-time guarantees which is both wellbased on theoretical foundations and practical from a software engineering and an efficiency point of view. Several aspects are essential to the USES approach: the resulting system is modular by structuring the task into a sequence of subtasks, which are tackled with appropriate methods. Generic and generative methods are used whenever possible. These principles lead to an understandable, maintainable, efficient, and provably correct system. This paper gives an overview of the methods used in the USES approach to WCET determination. A fully functional prototype system for the Motorola ColdFire MCF 5307 processor is presented, the implications of processor design on the predictability of behavior described, and experiences with analyzing applications running on this processor reported.