AN ATTEMPT IS DESCRIBED TO FIND THE BASIC PHYSICAL FACTORS DETERMINING CREEP IN CEMENT PASTE, AND SELECT AMONG THE EXISTING THEORIES ON CREEP THE CORRECT ONE BY EXPERIMENTAL INVESTIGATIONS. CEMENT PASTE AND CONCRETE SAMPLES WERE DRIED, LOADED, AND RESATURATED AT VARIOUS TEMPERATURES. ONLY ONE TYPE OF TEST DEFINED CLEARLY THE FACTORS DETERMINING CREEP; THIS TEST PROVED THAT THE SHEARING OR SLIDING OF SUB-MICROSCOPIC GEL PARTICLES WETTED BY WATER IS A MAJOR FACTOR IN CREEP. THEORIES RELATING TO THE DIMENSION OF CRITICAL SPACES IN CEMENT GEL, WHICH CAUSE DIMENSIONAL INSTABILITY IN CONCRETE STRUCTURES, WERE CONFIRMED BY USING ORGANIC LIQUIDS CONTAINING MOLECULES OF VARIOUS SIZES. /LCPC/A(A)/