The objective of this study is to evaluate patients with tumors of the central nervous system (CNS) for eligibility in the National Cancer Institute s research studies. These patients will undergo a series of procedures, usually including a complete medical history and physical examination; laboratory testing of blood, CSF, urine, bone marrow, or other samples; an evaluation of tumor location and size by x-rays, CT (computed tomography) or MRI (magnetic resonance imaging) scans, or nuclear medicine scans; lumbar puncture; electrocardiogram and echocardiogram; and procedures to evaluate the function of specific organs. A bone marrow biopsy is occasionally performed. Research samples may also be collected and stored to avoid having to do a painful test more than once. Tissue specimens collected during this process may be stored and used in future studies.