More than 550 Muslim women from Western countries have joined ISIS and moved to its proclaimed ‘Caliphate’ in Syria and Iraq. No extremist group has been able to attract so many female Western recruits so far, and their number continues to grow. This article is intended to explain the reasons behind such unprecedented success, the motivation of Western Muslims to join ISIS and their roles in the ‘Islamic State’. It also compares living conditions under ISIS’ rule with the expectation induced by ISIS’ recruiters in women from the West who had shown an interest to make hijra and join ISIS. Understanding these factors is vital to figure out how to stop this trend and to assess the security threat posed to the West by possible female returnees, or radicalised sympathizers who are unable to leave their countries of residence.