Introduction: Reliable markers of neuro-cognitive progression during the clinical course of Sturge-Weber syndrome (SWS) have not been established. In this prospective, longitudinal clinical research study of children with SWS, we have correlated the electro-clinical features, imaging characteristics and cognitive functions (IQ) in a single-center cohort. Methods: Gender, age, scalp EEG abnormalities (background attenuation, slowing, spike frequency), and extent of brain involvement on MRI were correlated with epilepsy variables and IQ in SWS children at baseline (n=65, 63 unilateral, 2 bilateral; mean age: 3.9 years, 3 months – 12.7 years) and at follow-up (n=38, mean follow-up: 2.3 years). Results: Girls (n=41) were younger (2.7 vs. 5.8 years, p<0.001), had earlier seizure onset (mean: 0.9 vs. 2.1 years; p=0.015) and shorter epilepsy duration (1.9 vs. 3.5 years; p=0.015) than boys; extent of brain involvement, seizure frequency and IQ showed no gender differences. Initial mean IQ was 80±20, and lower initial IQ was associated with EEG background abnormalities and extensive brain involvement (p<0.01). Lower IQ at follow-up was associated with initial EEG background abnormalities (p=0.001) and high spike frequency (p=0.003) but not extent of brain involvement. Interictal spikes were present in 20 patients but were lateralized to the unaffected hemisphere in 6 (30%). Conclusions: EEG background abnormalities and high spike frequency are better predictors of poor cognitive outcome in young SWS children than the extent of brain involvement on MRI; however, interictal spikes may often be falsely lateralizing. The observed gender differences in epilepsy characteristics warrant further studies in larger SWS cohorts.