THE SIGNIFICANCE OF CONCRETE COMPRESSIVE STRENGTH MEASUREMENT BY VARIOUS METHODS WAS INVESTIGATED. PAIRS OF SLABS FROM THREE CONCRETES WERE SUBJECTED TO GOOD AND POOR CURING. CORES AND PUSH-OUT CYLINDERS WERE REMOVED AT SIX STAGES UP TO 1 YEAR AND TESTED FOR STRENGTH. CORRESPONDING TESTS OF MOLDED CYLINDERS BROUGHT THE TOTAL SPECIMENS TO 216 CORES, 216 PUSH-OUT CYLINDERS, AND 270 MOLDED CYLINDERS. THE DATA INDICATE THAT TWO CONCEPTS OF STRENGTH SHOULD BE DISTINGUISHED: (1) STRENGTH AS A MEASURE OF LOAD-CARRYING CAPACITY IN STRUCTURES, AND (2) STRENGTH AS A MEASURE OF CONCRETE QUALITY AND UNIFORMITY. THE RELATION OF THE LATTER (DETERMINED BY STANDARD CYLINDER TESTS) TO THE FORMER (DETERMINED ON CORES FROM THE STRUCTURE) IS EXTREMELY VARIABLE. /AUTHOR/