Methodology: Eligible participants will include all living veterans with a physician diagnosis of ALS. Veterans with possible ALS will be identified through VA medical records, the Veterans Benefits Administration (VBA), and self-referral. Neurologists with expertise in ALS will review veterans' medical records to verify the diagnosis and determine eligibility. Upon enrollment, veterans will be asked to complete a brief telephone interview. Registry participants will also be contacted by telephone biannually to assess health and functional status. The VA may notify registry participants about clinical trials for which they may be eligible. A Scientific Review Committee will evaluate all studies that request use of registry data and/or access to Registry participants.