AbstractCondition Monitoring of civil structures is best accomplished by way of distributed sensors. Sensors capable of making distributed measurements allow for monitoring the entire structure. Optical fiber sensors are especially very attractive for this purpose, since they are geometrically versatile and they can be readily integrated within various types of structures and materials. The research presented here describes the development of a new optical fiber sensor system for measurement of structural strains based on white light interferometry. Individual sensors are linked in series and an optical switch provides for multiplexing of strain signals from various locations in the structure. Bragg grating type fiber optic sensors as well as strain gauges were employed for comparison and verification of strain signals as measured by the new system. The system provides capability for distributed sensing of strains in large structures.