Indonesian extremists have a long history of online activism, but links to the Islamic State (still better known in Indonesia by its former acronym ISIS) have raised questions about whether social media usage is significantly changing patterns of radicalisation and recruitment. The answer seems to be a qualified no, but ISIS propaganda seems nevertheless to be having an impact, persuading some Indonesians that the ‘caliphate’ in Syria and Iraq is a well-run state where devout Muslim families can find fulfilment. Where social media has made a difference is in its ability to turn anyone with a Twitter account into a potential propagandist, meaning that the ISIS message may start with friends and family linked into online networks but quickly reaches a much broader public.