This is a Phase I study of the agent, lenalidomide (CC-5013) in pediatric patients with CNS tumors. The primary objective is to determine the maximum tolerated dose of this agent and a recommended Phase II dose. Patients on this study are less than 22 years of age and have a recurrent, progressive or refractory CNS tumor. Patients are treated with lenalidomide given orally for 21 days of a 28 day cycle. Dose escalations were based on absence of toxicities for each dose level in course 1. The study has accrued quickly and has reached its accrual goals. The study is currently under analysis and results were presented at the Society of Neuro-Oncology in November 2008. A manuscript has been submitted.