Objective: To delineate factors that may contribute to maxillary hypoplasia requiring maxillary advancement surgery in individuals with nonsyndromic unilateral cleft lip and palate (UCLP). Methods: This retrospective, longitudinal study used lateral cephalometric radiographs and chart reviews of 16 nonsyndromic UCLP individuals who underwent Le Fort I maxillary advancement and 16 controls matched for cleft type, age, and gender. Cephalometric measurements were made at three time points (T1, T2, and T3): mean ages of 10.7, 13.3, and 15.8 years for the Le Fort group and 10.11, 12.9, and 15.7 years, respectively, for the control group. Information regarding team care, timing and number of surgical procedures, and number of congenitally missing teeth were determined from clinical records. Results: The Le Fort group had significant maxillary hypoplasia at all time points compared to the UCLP controls, indicated by midface length measurements, ANB and Wit's analysis ( p < .001). The Le Fort group had twice the number of palatal surgical procedures and number of missing teeth in the maxillary arch as compared with the cleft controls. Most of the control group had consistent team care, while most of the surgical group did not. Conclusions: Maxillary hypoplasia that will require a Le Fort I advancement can be determined as early as age 10. Multiple missing maxillary teeth, secondary palate procedures including pharyngeal flaps, and inconsistent team care with delayed orthodontic intervention are contributing factors to maxillary underdevelopment.