This document is about the contribution of the construction industry to the economy of Indonesia. The document examines work done to determine the detailed effects of investing in construction. The effects considered are those on the micro and macro economy of the people directly or indirectly employed by the construction industry. The work is based on surveys, which were carried out in Indonesia to investigate how the money invested in construction flows through the economy. It also examines at which point in the construction process income is received, and at which point it is spent. The results of these surveys were analyzed using statistical methods and combined with results from economic input-output modeling. The results were then used to build a system model.