To externally validate the admission prediction model for successful vaginal birth after cesarean (VBAC) using an ethnically diverse population. We have previously published a comparison between predicted and actual success rates using the prenatal intake calculator of the Maternal-Fetal Medicine Units Network prediction model (MFMU). Retrospective cohort study analyzing all women with at least one prior cesarean delivery attempting a trial of labor between 2007-2016 at a tertiary medical center. We investigate the difference between predicted and actual success rates using MFMU VBAC predictor model with variables collected upon admission. Participants were stratified into three probability-of-success groups: low (<35%), moderate (35-65%) and high (>65%). The primary outcome was the difference between predicted and actual success rates. Secondary outcomes include differences in intrapartum variables and perinatal outcomes between the three groups. P values were calculated with ANOVA, paired t-test, chi-squared test, or Fisher's exact test as appropriate. All analyses were done with STATA 14.2 614 women met the inclusion criteria. Actual VBAC rates did not differ from predicted rates when predicted chance of success was less than 65%, in either low (28.5% vs. 25.8%, p=0.79) or moderate groups (55.8% vs. 52.1%, p=0.37). However, in the high probability group, actual success rates were lower than predicted success rates (79.2% vs. 83.5%, p=0.02). Women in the higher probability groups were less likely to need augmentation of labor (76.2% vs. 74.3% vs. 40.9%, p<0.001), less likely to have diabetes (28.6% vs. 13.2% vs. 7.4%, p=0.001), more likely to have a midwife as primary provider (14.3% vs. 18.4% vs. 30.4, p=0.009), less likely to have elevated blood pressure (47.6% vs. 15.4% vs. 7.0%, p<0.001) during labor and less likely to need magnesium sulfate treatment (19.1% vs. 9.6% vs. 3.5%, p<0.001). There was no statistically significant difference in perinatal outcomes between the three groups. The published prediction model incorporating admission variables is predictive of VBAC success rates, but may slightly overestimate actual success rates in those with predicted success rates >65%. This model was more predictive of VBAC success than the prenatal intake admission calculator in our cohort.