THE MOON HAS BEEN GREATLY ALTERED BY LARGE IMPACTS THAT NOT ONLY CHANGE THE LUNAR SURFACE BUT THE MANNER IN WHICH TOPOGRAPHY AND CRUSTAL THICKNESS IS ALTERED RECORDS SOME OF THE MOST BASIC PROPERTIES OF THE MOON AT THE TIME OF IMPACT (~4 GA FOR MOST LARGE BASINS) SUCH AS ITS THERMAL GRADIENT AND ITS RHEOLOGY. PREVIOUS IMPACT MODELING OF EXCAVATION THROUGH TRANSIENT CRATER COLLAPSE SUGGESTS THAT BASIN DIAMETERS AND CRUSTAL THICKNESS VARIATIONS ARE PRIMARILY DUE TO IMPACTOR SIZE AND VELOCITY THE THICKNESS OF THE PRE-IMPACT CRUST AND THE LUNAR THERMAL GRADIENT AT THE TIME OF IMPACT. HOWEVER THE FINAL DEPTH OF BASINS IS NOT REACHED FOR 10S OF MILLIONS OF YEARS AFTER COOLING AND ISOSTATIC READJUSTMENT. THESE PROCESSES ARE CONTROLLED BY THE HEAT OF IMPACT THE BACKGROUND THERMAL GRADIENT AND THE TEMPERATURE-DEPENDENT VISCOSITY STRUCTURE. THE THERMAL GRADIENT IS THUS THE UNIFYING PARAMETER IN BOTH PHASES OF BASIN EVOLUTION AND CAN BE CONSTRAINED THROUGH SELF-CONSISTENT MODELING OF THE COMPLETE EVOLUTION OF A SUITE OF BASINS THAT RANGE IN SIZE AGE AND PROVINCE. THERE ARE TWO PUZZLING CHARACTERISTICS OF LUNAR BASINS: (1) THERE IS AN IDEAL BASIN DIAMETER FROM WHICH MASCONS (EXCESS MASS AT THE BASIN CENTER) DEVELOP (THE GOLDILOCKS QUESTION) AND (2) NEARSIDE BASINS ARE GENERALLY LARGER THAN FARSIDE BASINS (THE BASIN SIZE DICHOTOMY QUESTION). FOR THE GOLDILOCKS QUESTION WE HYPOTHESIZE THAT IMPACT BASINS WILL ONLY EVOLVE INTO MASCONS WHEN A MECHANICAL COUPLING FORMS BETWEEN THE INNER AND OUT BASIN DUE TO COOLING PRIOR TO SIGNIFICANT ISOSTATIC UPLIFT. AFTER TRANSIENT CRATER COLLAPSE THE INTERIORS OF MOST BASINS ARE FOUND TO BE IN A SUB-ISOSTATIC STATE AND NORMALLY ISOSTATIC UPLIFT CANNOT EXCEED ISOSTATIC EQUILIBRIUM. HOWEVER THE FORMATION OF THIS MECHANICAL COUPLING ALLOWS THE ISOSTATIC UPLIFT OF THE CRUSTAL COLLAR (THE THICKENED REGION OF CRUST NEAR THE OUTER BASIN) TO GIVE AN ASSIST TO THE INNER BASIN ALLOWING IT TO RISE INTO A SUPERISOSTATIC STATE (A MASCON). OUR HYPOTHESIS SEEKS TO EXPLAIN WHY THIS HAPPENS OVER A LIMITED RANGE OF BASIN SIZE.