Disclosed herein are methods for decreasing Ataxin 2 mRNA and protein expression. Such methods are useful to treat, prevent, or ameliorate Ataxin 2 associated diseases, disorders, and conditions. Such Ataxin 2 associated diseases include spinocerebellar ataxia type 2 (SCA2), amyotrophic lateral sclerosis (ALS), and parkinsonism. Provided are methods for reducing expression of Ataxin 2 (ATXN2) mRNA and protein in an animal. Such methods are useful to treat, prevent, or ameliorate neurodegenerative diseases, including spinocerebellar ataxia type 2 (SCA2), amyotrophic lateral sclerosis (ALS), and parkinsonism by inhibiting expression of Ataxin 2 in an animal.