Purpose To investigate the causes of glaucoma in children following removal of cataracts. Methods In total, 24 patients (37 eyes) with uncomplicated congenital cataracts who developed glaucoma following cataract removal were studied retrospectively. Cataract morphology, surgical technique, postoperative complications, time to glaucoma onset, gonioscopic findings, the presence of microcornea, and the histopathologic characteristics of the filtration angle in one case were the studied parameters. Results We found a bimodal onset of glaucoma. Early-onset glaucoma occurred at a mean age of 6 months in 15 eyes and delayedonset glaucoma at a mean age of 12 years in 22 eyes. Early-onset glaucoma was significantly (P ¼ 0.018) more likely to be due to angle closure. With delayed-onset glaucoma, the filtration angle is open in 86% of eyes and significantly (P ¼ 0.006) more eyes in the delayed-onset group had microcornea. Conclusions Performing cataract surgery very early in life in microphthalmic eyes and leaving residual lens material increases the risk for glaucoma. We recommend a prophylactic iridectomy in eyes at risk for pupillary block. Eyes with delayed-onset glaucoma have open filtration angles but with findings consistent with incomplete development of filtration structures. Early age at cataract extraction and microcornea are risk factors for delayed-onset glaucoma.