Despite many uncertainties, industrial fields such as energy (eg, oil rigs), utilities infrastructure (eg, telecommunications), space systems, transportation systems, construction, and manufacturing make large and mostly irreversible investments in systems with potentially long life cycles. The life cycle value of such systems may be increased significantly by designing in the flexibility to make future changes. This paper presents a systematic methodology for designers to identify flexible design opportunities (FDOs) more comprehensively and earlier in the system design process. The methodology guides designers to generate flexible design concepts that can be assessed, selected, and integrated into a design during an early stage of the design process. We demonstrate and validate the FDO methodology on a case in the offshore drilling industry.