THIS RESEARCH ADDRESSES UTILIZATION OF NATURALLY-OCCURRING VARIATION TO ENRICH GENETIC DIVERSITY AND ACCELERATE BREEDING PROGRESS IN ONE OF THE MOST ECONOMICALLY IMPORTANT AND GENETICALLY VULNERABLE US CROPS, COTTON. NATURALLY OCCURRING DAY-NEUTRAL (BREEDER-FRIENDLY) COTTONS CAPTURE MUCH OF THE EXOTIC DIVERSITY AVAILABLE. PRIOR FUNDING REVEALED MANY OF THESE EXOTIC COTTONS TO CONFER IMPROVEMENTS TO ELITE GERMPLASM. HERE, A SELECTION INDEX APPLIED TO PRIOR PHENOTYPING PRIORITIZED 50 LINES FOR BACKCROSSING TO ONE OF TWO ELITE CULTIVARS THEN PHENOTYPING IN 3 ENVIRONMENTS TO PRIORITIZE 10 CROSSES FOR IN-DEPTH EVALUATION. GENETIC ANALYSIS ('QTL MAPPING') TO ASSESS EXOTIC ALLELES FOR CONTRIBUTIONS TO THE ELITE GENE POOL WILL BE BASED ON 3 ENVIRONMENTS FOR 100 PROGENY PER CROSS (NOTING THAT MANY ALLELES MAY SEGREGATE IN MORE THAN 1 CROSS). ELITE ALLELES THAT CONSISTENTLY CONFER IMPROVEMENTS AGAINST A BACKGROUND OF MULTIPLE EXOTIC ALLELES WILL BE IDENTIFIED BASED ON SIX ENVIRONMENTS WITH 500 INDIVIDUALS EACH, EVALUATED AGAINST BACKGROUNDS OF 5 (3 ENVIRONMENTS) OR 25 (3 ENVIRONMENTS) EXOTICS. COMPARING ELITE CULTIVARS DES 56 AND ACALA MAXXA (TO BE USED IN CROSSES) MAY DISCERN DIFFERENCES IN HOW THESE KEY REPRESENTATIVES OF CORE US GERMPLASM PERFORM IN EXOTIC CROSSES. THE HYPOTHESIS THAT THE ELITE GENE POOL ITSELF EXPERIENCES LINKAGE DRAG WHICH CAN BE MITIGATED BY THIS EXOTIC GERMPLASM WILL BE TESTED. PARTNERSHIP BETWEEN A PLANT BREEDER AND A GENOME BIOLOGIST WILL INTEGRATE TRAINING IN FIELD-BASED BREEDING WITH EFFECTIVE UTILIZATION OF GENOMIC DATA AND TOOLS TOWARD MITIGATING GENETIC VULNERABILITY, IN A MANNER APPLICABLE TO MANY OTHER CROPS.