The Interministerial Commission on Economic Structure (ICES) was asked to recommend infrastructure investments to sustain economic growth. In its considerations, ICES affirmed two principles in considering the allocation of resources: The knowledge infrastructure of the country, as well as its physical infrastructure, is an important foundation for economic growth; and attempting to stimulate economic growth can result in dilemma-like negative side effects, so that investments must address not only economic growth but also the accompanying dilemmas. Five such dilemmas were identified. ICES formed a study group called Knowledge InfraStructure (KIS) to recommend investments based on these principles. This report attempts to clarify what is meant by knowledge infrastructure, illuminate the relationships among economic growth, physical investment, and knowledge investment, and identify areas for knowledge investment consistent with the principles.