BACKGROUND: SURGEONS PROVIDE PATIENT CARE IN COMPLEX HEALTH CARE SYSTEMS AND MUST BE ABLE TO PARTICIPATE IN IMPROVING BOTH PERSONAL PERFORMANCE AND THE PERFORMANCE OF THE SYSTEM. THE ACCREDITATION COUNCIL FOR GRADUATE MEDICAL EDUCATION (ACGME) VASCULAR SURGERY MILESTONES ARE UTILIZED TO ASSESS VASCULAR SURGERY FELLOWS' (VSF) ACHIEVEMENT OF GRADUATION TARGETS IN THE COMPETENCIES OF SYSTEMS BASED PRACTICE (SBP) AND PRACTICE BASED LEARNING AND IMPROVEMENT (PBLI). WE INVESTIGATE THE PREDICTIVE VALUE OF SEMIANNUAL MILESTONES RATINGS FOR FINAL ACHIEVEMENT WITHIN THESE COMPETENCIES AT THE TIME OF GRADUATION. METHODS: NATIONAL ACGME MILESTONES DATA WERE UTILIZED FOR ANALYSIS. ALL TRAINEES ENTERING THE 2-YEAR VASCULAR SURGERY FELLOWSHIP PROGRAMS IN JULY 2016 WERE INCLUDED IN THE ANALYSIS (N = 122). PREDICTIVE PROBABILITY VALUES (PPVS) WERE OBTAINED FOR EACH SBP AND PBLI SUB-COMPETENCIES BY BIANNUAL REVIEW PERIODS, TO ESTIMATE THE PROBABILITY OF VSFS NOT REACHING THE RECOMMENDED GRADUATION TARGET BASED ON THEIR PREVIOUS MILESTONES RATINGS. RESULTS: THE RATE OF NONACHIEVEMENT OF THE GRADUATION TARGET LEVEL 4.0 ON THE SBP AND PBLI SUB-COMPETENCIES AT THE TIME OF GRADUATION FOR VSFS WAS 13.1-25.4%. AT THE FIRST TIME POINT OF ASSESSMENT, 6 MONTHS INTO THE FELLOWSHIP PROGRAM, THE PPV OF THE SBP AND PBLI MILESTONES FOR NONACHIEVEMENT OF LEVEL 4.0 UPON GRADUATION RANGED FROM 16.3-60.2%. SIX MONTHS PRIOR TO GRADUATION, THE PPVS ACROSS THE 6 SUB-COMPETENCIES RANGED FROM 14.6-82.9%. CONCLUSIONS: A SIGNIFICANT PERCENTAGE OF VSFS DO NOT ACHIEVE THE ACGME VASCULAR SURGERY MILESTONE TARGETS FOR GRADUATION IN THE COMPETENCIES OF SBP AND PBLI, SUGGESTING A NEED TO IMPROVE CURRICULA AND ASSESSMENT STRATEGIES IN THESE DOMAINS ACROSS VASCULAR SURGERY FELLOWSHIP PROGRAMS. REPORTED MILESTONES LEVELS ACROSS ALL TIME POINT ARE PREDICTIVE OF ULTIMATE ACHIEVEMENT UPON GRADUATION AND SHOULD BE UTILIZED TO PROVIDE TARGETED FEEDBACK AND INDIVIDUALIZED LEARNING PLANS TO ENSURE GRADUATES ARE PREPARED TO ENGAGE IN PERSONAL AND HEALTH CARE SYSTEM IMPROVEMENT ONCE IN UNSUPERVISED PRACTICE.