Background and Objectives: Associations between training length and clinical preparedness are unknown. We compared assessments of clinical preparedness for family medicine graduates from 3-year and 4-year training programs. Methods: In this prospective case-control study, we compared responses from two surveys, which occurred 3 months after graduates started their first job. One survey was conducted by a supervising physician. The other was conducted by a clinic staff member who rated family medicine graduates from both 3-year and 4-year programs. Results: Our study included 403 graduates of 3-year programs, 185 who trained in 4-year programs with 36 months of training (4YR-36) and 274 who trained in 4-year programs with 48 months of training (4YR-48). Physician assessor ratings were similar across study groups on 18 of 21 Entrustable Professional Activities. The 4YR-48 graduates were rated higher for “practicing independently” on providing a usual source of comprehensive, longitudinal medical care for people of all ages (86.5% vs 77.9%); managing prenatal (63.1% vs 41.2%); and labor, delivery, and postpartum care (41.4% vs 25.7%). For five care process areas, physician assessors were more likely to rate 4YR-48 graduates as having “no challenges” with speed/timing related health care visits (91.9%) compared to 3YR graduates (82.4%). We noted no differences according to study group for staff member assessors. Conclusions: We found several differences in clinical preparedness according to length of training in this pilot study. Comprehensive longitudinal care, including prenatal and maternity care, were rated higher among graduates of 4YR-48 programs.