To describe the impact of periventricular leukomalacia (PVL) on gross motor function, data on 59 children (37 males, 22 females) with a gestational age (GA) of 34 weeks or less with cerebral palsy (CP) due to PVL grade I (n=20), II (n=13), III (n=25), and IV (n=1) were studied; (mean GA 29wk 4d [SD 4wk 6d]; mean birthweight 1318g [SD 342]). Two independent raters used the Gross Motor Function Classification System (GMFCS) at four time points: T1, mean corrected age (CA) 9 months 15 days (SD 2mo 6d); T2, mean CA 16 months (SD 1mo 27d); T3, mean CA 24 months 27 days (SD 2mo 3d); and T4, median age 7 years 6 months (range 2y 2mo–16y 8mo). Interrater reliability and stability across time with respect to the total cohort were κ≥0.86 and ρ≥0.74 respectively. The association between PVL and gross motor outcome at T4 was strong (positive and negative predictive values 0.92 and 0.85 respectively). The proportion of children who remained in the same GMFCS level increased from 27% (T1–T4) to 53% (T2–T4) and 72% (T3–T4). PVL grade I to II, as diagnosed in the neonatal period, has a better functional mobility prognosis than PVL grade III–IV. These findings have implications for habilitation counselling and intervention strategies.