PERTINENT ENGINEERING AND SCIENTIFIC LITERATURE ON THE NATURE AND BEHAVIOR OF MOISTURE AS RELATED TO SOIL FREEZING ARE REVIEWED. CONSIDERED INITIALLY IS THE BASIC STRUCTURAL NATURE OF WATER, OF ICE, AND OF IONIC SOLUTIONS. THIS IS FOLLOWED BY SUMMARIZATION OF THE FORCES RESPONSIBLE FOR MOISTURE ADSORPTION IN CLAY-WATER SYSTEMS, THE STRUCTURE AND PROPERTIES OF THE ADSORBED WATER, AND THE CONSEQUENT EFFECT UPON SUPERCOOLING AND FREEZING OF THIS WATER. HAVING ESTABLISHED A BASIC PHYSICAL AND CHEMICAL BACKGROUND, THE PAPER PROCEEDS THROUGH A BRIEF REVIEW OF WHAT IS KNOWN OF INSERVICE MOISTURE CONDITIONS UNDER PAVEMENTS, AND HOW THESE MOISTURE CONDITIONS MAY CHANGE WITH TIME. FINALLY, CONSIDERATION IS GIVEN TO THE TECHNIQUES OF DETERMINATION OF SERVICE MOISTURE QUANTITIES, AND TO THE PRINCIPLES OF CONTROL OF SUCH MOISTURE QUANTITIES. /AUTHOR/