Amyotrophic lateral sclerosis (ALS) is an unrelenting progressive neurodegenerative disease causing progressive weakness, ultimately leading to death. Despite aggressive research, the pathways leading to neuronal death are incompletely understood. Riluzole is the only drug clinically proven to enhance survival of ALS patients, but its mechanism of action is not clearly understood. In this article, the proposed pathophysiology of ALS is reviewed including glutamate excitotoxicity, oxidative stress, mitochondrial dysfunction, autoimmune mechanisms, protein aggregation, SOD1 accumulation, and neuronal death. Based on these mechanisms, past major ALS drug studies will be reviewed as well as promising current ALS drug studies, focusing on the advancement of these studies from the bench to the patient's bedside.