Juan Diego Díaz is an ethnomusicologist with a geographic research interest in Africa and its diaspora, particularly Brazil and West Africa. He explores how African diasporic musics circulate and transform across the Atlantic and how they serve individuals and communities in identity formation. His book Africanness in Action (Oxford University Press, 2021) focuses on how musicians from Bahia, Brazil understand and negotiate essentialist notions about African music and culture. He is also a long-term Capoeira Angola practitioner and has led capoeira, berimbau, and samba ensembles.

Previous to teaching at UC Davis, Juan Diego held posts as a lecturer at the University of Ghana and postdoctoral fellow at the University of Essex, the latter funded by the Social Sciences and Humanities Research Council of Canada. The funded research investigates the music of the descendants of freed enslaved Africans who resettled from Brazil to Ghana, Togo, and Benin during the nineteenth century. This research has produced a book titled Tabom Voices: A History of the Ghanaian Afro- Brazilian Community in Their Own Words (2016) and the documentary film Tabom in Bahia  (co-directed with Nilton Pereira, 2017), documenting the visit of a Ghanaian master drummer to Bahia, Brazil.

His articles have appeared in journals such as Ethnomusicology, Ethnomusicology Forum, Analytical Approaches to World Music, and Latin American Music Review.