EU-MIDIS is the first systematic large-scale attempt to survey selected immigrant, ethnic minority and national minority groups in all 27 EU Member States about their experiences of discrimination and victimisation. As such, the survey faced a number of technical challenges that had to be addressed from the outset, and which are related in detail in this report in order to communicate how the survey met the various demands for successfully conducting high quality and robust research on 'difficult to survey' groups.