The Internalized Stigma of Mental Illness (ISMI) scale is a 29-item questionnaire measuring self-stigma among persons with psychiatric disorders. It was developed with substantial consumer input and has been widely used, but its psychometric qualities have not been comprehensively evaluated across multiple versions. Here we review the 55 known versions, and provide the 47 available versions, including: Arabic, Armenian, Bengali, Bulgarian, Chinese (Mainland, Taiwan, Hong Kong), Croatian, Dutch, English (USA, South Africa), Estonian, Farsi, Finnish, French, German, Greek, Hebrew, Hindi, Japanese, Khmer, Korean, Lithuanian, Lugandan, Maltese, Polish, Portuguese (Portugal, Brazil), Romanian, Russian, Samoan, Slovenian, Spanish (Spain), Swahili, Swedish, Tongan, Turkish, Urdu, and Yoruba, and qualitative English and Swahili versions, as well as versions for depression, schizophrenia, substance abuse, eating disorders, epilepsy, inflammatory bowel disease, leprosy, smoking, parents and caregivers of people with mental illness, and ethnicity. The various versions show reliability and validity across a wide range of languages, cultures, and writing systems. The most commonly reported findings of studies using the ISMI are that internalized stigma correlates with higher depression, lower self esteem, and higher symptom severity. Initial studies of ways to reduce internalized stigma are promising and warrant further investigation.