Software engineering projects are complex sociotechnical systems whose behavior is the result of many technical and human factors, from personnel skills to development tools and processes to business goals. Project managers must identify the right combination of these factors to obtain the desired results. In many fields, managers get support from sophisticated decision support systems, but these haven't yet entered the software engineering mainstream. A hybrid modeling approach can quickly produce process models that can provide project managers accurate predictions, help them design the desired project trajectory, and validate process changes. The NASA Software Engineering Laboratory process provides a case study.