Background: In this paper we present a systematic review of the evidence on the use of social media by people with intellectual disability. Method: Ten primary studies published in the English language between January 2000 and June 2014 were identified from electronic database searches (CINAHL, PsychInfo, PubMed, Web of Knowledge, and Scopus), correspondence with experts, and citation tracking. Results: Nine themes were identified through thematic analysis of the texts: "safety and safeguarding," "social identity," "level of usage," "support," "relationships," "happiness and enjoyment," "communication and literacy skills," "cyber-language and cyber-etiquette," and "accessibility/design". Conclusion: Examination of these themes revealed that some people with intellectual disability are having positive experiences using social media in terms of friendships, development of social identity and self-esteem, and enjoyment. However, barriers that stop people with intellectual disability from successfully accessing social media were identified as being safeguarding concerns, difficulties caused by literacy and communication skills, cyber-language, cyber-etiquette, and accessibility (including lack of appropriate equipment).