Background: The ACGME Milestone Project created a competency-based trainee assessment tool. Subcompetencies (SCs) are scored on a 5-point scale; level 4 is recommended for graduation. The 2018 Milestones Report found that across subspecialties, not all graduates attain level 4 for every SC. Objective: The objective was to describe the number of pediatric emergency medicine (PEM) fellows who achieve ≥ level 4 in all 23 SCs at graduation and identify SCs where level 4 is not achieved and factors predictive of not achieving a level 4. Methods: This is a multicenter, retrospective cohort study of PEM fellows from 2014 to 2018. Program directors provided milestone reports. Descriptive analysis of SC scores was performed. Subanalyses assessed differences in residency graduation scores, first-year fellowship scores, and the rate of milestone attainment between fellows who did and did not attain ≥ level 4 at graduation. Results: Data from 392 fellows were obtained. There were no SCs in which all fellows attained ≥ level 4 at graduation; the range of fellows scoring < level 4 per SC was 7% to 39%. A total of 67% of fellows did not attain ≥ level 4 on one or more SC. While some fellows failed to attain ≥ level 4 on up to all 23 SCs, 26% failed to meet level 4 on only one or two. In 19 SCs, residency graduation and/or first year fellow scores were lower for fellows who did not attain ≥ level 4 at graduation compared to those who did (mean difference = 0.74 points). Among 10 SCs, fellows who did not attain ≥ level 4 at graduation had a faster rate of improvement compared to those who did attain ≥ level 4. Conclusion: In our sample, 67% of PEM fellows did not attain level 4 for one or more of the SCs at graduation. Low scores during residency or early in fellowship may predict difficulty in meeting level 4 by fellowship completion.