CrossCheck, an approach to the application-specific integrated circuit ASIC test problem that is based on embedding test structures into the base array of the ASIC, is discussed. With a specially designed storage element called the cross-controlled latch, CrossCheck combines controllability and observability to produce a highly testable ASIC having minimal area and performance overhead. CrossCheck is a designer-transparent solution that imposes none of the rules and restrictions of other design-for-testability (DFT) methodologies. In CrossCheck, test structures are embedded into the ASIC base, rather than added by the designer to the schematic as with scan or built-in self-test (BIST) methodologies. The built-in observability also offers easier debugging and diagnostics methods to the designer. Experimental results that demonstrate the potential of the CrossCheck method on a broad range of ASIC styles and sizes are presented.