Â© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Design decisions for complex systems often can be made or informed by a variety of information sources. When optimizing such a system, the evaluation of a quantity of interest is typically required at many different input configurations. For systems with expensive to evaluate available information sources, the optimization task can potentially be computationally prohibitive using traditional techniques. This paper presents an information-economic approach to the constrained optimization of a system with multiple available information sources. The approach rigorously quantifies the correlation between the discrepancies of different information sources, which enables the overcoming of information source bias. All information is exploited efficiently by fusing newly acquired information with that previously evaluated. Independent decision-makings are achieved by developing a two-step look-ahead utility policy and an information gain policy for objective function and constraints respectively. The approach is demonstrated on a one-dimensional example test problem and an aerodynamic design problem, where it is shown to perform well in comparison to traditional multi-information source techniques.