When it comes to human trafficking, hype often outweighs evidence. All too often, the discourse on traffickingincreasingly absorbed under discussions of so-called 'modern slavery' toois dominated by simplistic treatments of a complex problem, sweeping claims and dubious statistics [1-3]. Such an approach might help to win attention, investment and support for an anti-trafficking agenda in the short term, but ultimately risks causing credibility problems for the entire field and contributing to ineffective, even harmful, interventions [see, e.g., 2, 4-6]. From the 1990s onwards, levels of interest and investment in counter-trafficking expanded rapidly [3, 7, 8]. In tandem, the literature on trafficking has proliferated [9, 10]. Yet, actual empirical (data-driven) research remains relatively rare [11-14]. Of course, non-empirical approaches have value toofor example in challenging how we conceptualise trafficking or highlighting tensions in governments' or businesses' commitments to anti-trafficking measures. Nevertheless, empirical research is clearly crucial to advance understanding of the trafficking phenomenon and shape nuanced, evidence-informed policy and practice. Even where empirical research exists, its quality can be highly variable, with many publications (even peer-reviewed ones) found to fall short of even rudimentary scientific standards [13, 15]. Additionally, there is a particular dearth of rigorous, independent evaluations of interventions [7, 13]despite the many millions of dollars spent thus far on anti-trafficking efforts worldwide [12, 16]. Before proceeding, it is worth acknowledging some fundamental tensions in researching human trafficking. First, trafficking is not a neatly delineated phenomenon that can be consistently identified and readily counted [1, 2]. Instead, it is a relatively fuzzy social construct that exists upon what is increasingly recognised as a 'continuum of exploitation' running from decent conditions through to severe abuses [17]. Second,