Dr. Richard Barohn and Dr. Mazen Dimachkie lead this publication on Motor Neuron Disease. Focus is on ALS, with inclusion of primary lateral sclerosis, primary muscular atrophy, leg amyotrophic diplegia, brachial amyotropic diplegia, and isolate bulbar ALS. Among the topics presented are. Patterns of weakness, classification of motor neuron disease  & clinical diagnosis of sporadic ALS;  Potential environmental factors in ALS;  Neuropathology;  Spinal muscular atrophy; Complementary and alternative therapies in ALS frontotemporal dysfunction and dementia in ALS;  Symptoms management and end of life care;  Research approaches to slowing progression of ALS; Familial ALS; Kennedy disease and more. Information in this issue presents: Description of the problem (Incidence, Prevalence, Severity, Natural history); 2. Review of pertinent data;  Controversial areas discussing aspects such as areas of practice for which there are disagreements and why? What are the arguments and counter arguments and what data support them?;  Conclusions using levels of clinical evidence that support or refute an intervention. Procedural steps are provided for diagnostic and treatment discussions along with clinical cases.