Variety trials conducted by the University of California and San Joaquin Valley Cotton Board over a period of many years have included both fiber and yarn testing programs for both Acala Upland and Pima cotton varieties entered in these testing programs.   Since testing programs have been quite consistent in including hvi, AFIS and some advanced testing of yarns produced out of cotton from the same field trials where fiber samples were tested, comparisons are possible between tested fiber and yarn characteristics.  General relationships identified over multiple years and correlations between specific fiber and yarn characteristics used as indices of strength, fineness, uniformity and some limited other parameters will be discussed.