To evaluate the “marginalization thesis” which posits that marginalizedpopulations are more likely to engage in the undeclared economy, a 2013Eurobarometer survey of six South-East European countries is analysed.Findingthat some marginalized populations (e.g., those having difficulties payinghousehold bills, the unemployed, younger people) are significantly morelikelytoparticipate inundeclared work, but others are not (e.g., poorer nations,women, those with fewer years in formal education, those living in ruralareas),theoutcome is a call for a more variegated and nuanced understanding of themarginalization thesis. The paper then discusses the theoretical and policyimplications.