Pharmaceutical compositions and single unit dosage forms of thalidomide and pharmaceutically acceptable prodrugs, salts, solvates, hydrates, or clathrates are disclosed. Also disclosed are methods of treating and preventing diseases and conditions such as, but not limited to, leprosy, chronic graft-vs-host disease, rheumatoid arthritis, sarcoidosis, an inflammatory condition, inflammatory bowel disease, and cancer using the novel dosage forms disclosed herein.