Personal schedules allow workflow participants to improve their performance of activity executions. Participants are no longer surprised by the entries in their work-lists but receive advance information about (potential) future activity assignments, allowing better possibilities for work-planning. The personal schedule system is based on a probabilistic workflow time management system using duration histograms. A personal schedule collects future activity assignments together with their probability and their timing requirements and allows to analyze the workload of a participant and to support the scheduling of activities with the goal of reduced turn-around times and reduced number of violations of temporal constraints.