In recent years there has been considerable interest in business process redesign. A process model may be redesigned by combining various tasks and services according to best practices so as to satisfy predefined business rules and constraints to achieve a specific purpose. This purpose may be stated in terms of functional goals (such as desired or acceptable process behavior) and non-functional goals like cost, time and quality of service. There are many ways to redesign a process instance by applying improvements such as: making a task optional, replacing a task by another faster task (or service), task postponement, task combination, task splitting, task restructuring, etc. Given many such alternatives, there is no systematic way of evaluating their costs and benefits, and the tradeoffs among them. We describe a novel approach based on a formal model to optimize the “benefits” or net effects of a redesign with respect to a baseline design and show how it can be used to evaluate and compare alternative models at both design and run time.