The etiology of thyroid eye disease (TED) is multifactorial, and while certain risk factors are well known, ongoing research is disclosing new internal and external risk factors. Risk factors include, but are not limited to, thyroid dysfunction, age, sex/gender, geographic prevalence and ethnicity, family history and genetics, anatomic risk factors, environmental factors and social habits, autoimmune diseases, myasthenia gravis, diabetes mellitus, HIV, vitamin D, selenium, cholesterol, obesity, obstructive sleep apnea, and the microbiome. There is likely significant interplay among multiple factors in the pathogenesis of TED, and this remains an active and expanding area of study and research. Improving modifiable risk factors is important in reducing the chance of TED developing in people with Graves’ and in reducing severity in those who are already affected.