The overall objective of this study is to understand the political economy of migrant detention in Libya, in both the official and non-official detention systems. The study was launched in October 2018 and the report was finalized in April 2019. The study was conducted by means of a qualitative approach, based on primary field research spanning four research modules: literature review, initial screening of detention centres in Libya, primary field interviews with migrants and with a variety of key informants (armed groups, authorities, smugglers, detention-centre staff, programme implementers). The methodology was route focused and, as such, involved interviews in four countries: Niger, Libya, Italy and Malta. A total of 85 key informant interviews were conducted and 75 in-depth interviews were conducted with migrants (160 in-depth interviews in total).