Thomas's research on clothing and fashion spans traditional textile production in the Guatemalan highlands, the manufacture and circulation of “knockoff" fashions in Central America, and the efforts of fashion industry professionals in the United States and United Kingdom to address pressing problems of environmental degradation and labor exploitation associated with global apparel supply chains.

Her first book, Regulating Style: Intellectual Property Law and the Business of Fashion in Guatemala (University of California Press, 2016), is based on long-term research with indigenous Maya apparel manufacturers who make clothing that features unauthorized reproductions of fashion brands. She examines the rise of “knockoff" fashion in Central America amidst the politics of race and indigeneity, efforts by the Guatemalan state and international institutions to promote entrepreneurship and national development after nearly four decades of armed conflict, and the globalization of intellectual property regimes that criminalize practices of brand “piracy." The book also broadens out to explore the neocolonial contours of the global fashion system. She argues that trademark law enforcement is an important part of how the fashion industry regulates style along the lines of race, class, gender and geography.

Her ongoing research in Latin America extends to the forms of moral and legal reckoning that hold sway in indigenous communities and the efforts of nation-states to regulate economic practices that are disparaged as illegal and informal. She has edited a set of collections on these topics, including special issues of Latin American Politics and Society, Critique of Anthropology, and PoLAR: Political and Legal Anthropology Review. In a co-edited volume entitled Securing the City: Neoliberalism, Space, and Insecurity in Postwar Guatemala (Duke University Press, 2011), she examined state and community-level responses to mounting insecurities and widespread impunity for violent crime in Guatemala in relation to processes of economic and legal reform.

Her current book project describes the politics of environmental sustainability and labor rights from the perspectives of designers, marketers, and brand and supply chain managers at fashion and footwear firms in London, San Francisco, and Portland, Oregon. Tentatively titled, Sustainability in the Making: Labor, Ethics, and Ecology in the Global Fashion Industry, the book narrates how people who work in the fashion and footwear industry are attempting to build more environmentally sustainable and ethical supply chains. Rather than gauging the economic or ecological efficacy of these efforts, her research has focused on the ways that evolving business strategies reflect the emergence of new and different social identities, relationships to materials and technologies, moral sentiments and commitments, and meanings of work and labor among white-collar employees. The project engages conversations on material culture and materiality, ecology and environmentalism, the meaning and practice of sustainability, changing urban landscapes and processes of gentrification, corporate ethics, and cultures of contemporary capitalism.