Abstract: A test fixture for testing a specimen under compressive or tensile load under close, reproducible tolerances and conditions. Confronting platens having surfaces which act against the specimen are provided with an in-line wedge assembly which drives the platens to load the specimen. The platens and wedge assembly are positioned between the top and base of a frame assembly. The top and base are connected by side plate members which are tensioned when the wedge assembly is operated to load the specimen via the platens. The test fixture also has a load cell in line with the platens and which is acted against by the platens to continuously sense the load applied to the specimen.