Neuromuscular diseases are a broadly defined group of disorders that all involve injury or dysfunction of peripheral nerves or muscle. The site of injury can be in the cell bodies (i.e., amyotrophic lateral sclerosis [ALS] or sensory ganglionopathies), axons (i.e., axonal peripheral neuropathies or brachial plexopathies), Schwann cells (i.e., chronic inflammatory demyelinating polyradiculoneuropathy), neuromuscular junction (i.e., myasthenia gravis or Lambert-Eaton myasthenic syndrome), muscle (i.e., inflammatory myopathy or muscular dystrophy), or any combination of these sites. Some neuromuscular diseases are also associated with central nervous system disease, such as ALS, but most are restricted to the peripheral nervous system. The multitude of possible sites of injury can make neuromuscular diseases difficult to diagnose. Here the author reviews key features of the clinical presentation that help localize the site of injury and some basic tenets of electromyography. He then shares several pearls in diagnosing and treating patients with specific neuromuscular diseases.