The feasibility of using cathodoluminescence (CL) and scanning acoustic microscopy (SAM) to measure residual stresses and to map their spatial distribution was investigated. Both techniques were utilized to obtain qualitative and quantitative information on stresses in the vicinity of fibers in pressureless sintered fiber reinforced composites. Both techniques reveal that the stresses are high in close vicinity with the fiber reinforcements and decrease rapidly with increasing distance from the fiber/matrix interface. CL is a surface technique that requires the fibers to be exposed to the surface. SAM is a bulk technique that gives information on residual stresses when fibers are embedded in the matrix. The former can be applied to nonmetallic materials such as semiconductors, ceramics, and glasses; the latter can be applied to metallic materials as well.