An archivist, librarian, and writer, Güereña specializes in ethnic and multicultural archives. He is a native of Santa Barbara, California. His B.A. degree is from Westmont College. He received the MLS from the University of Arizona, where his emphasis was in library services to Latinos, and in library administration.
Since 1989 he has been Director of the California Ethnic and Multicultural Archives, in the University Library of the University of California, Santa Barbara. He also serves as the Chicano Studies Librarian. Previously, he headed the Colección Tloque Nahuaque (Chicano research library) in that institution, where he also served as assistant head of the Reference Department, overseeing the ethnic studies units and the Curriculum Laboratory, as part of the department's management team.
As an adjunct faculty member in the Department of Chicano Studies, he has taught the four-unit course Documentary Research Methods in Chicano Studies.
During 1980-1983 he worked for the Santa Barbara Public Library System (1980-1983) directing the library system's ethnic and multicultural outreach program and managed one its branch libraries.
He has served on the executive board of the Society of California Archivists. He is currently active with the Archives and Archivists of Color Round Table of the Society of American Archivists.
He is a past president of REFORMA, the National Association to Promote Library and Information Services to Latinos and the Spanish Speaking, and in 1992 REFORMA honored him with its "Librarian of the Year" award.
He has served on the governing Council of the American Library Association, chaired various ALA committees including the Reference and Adult Services Division's Committee on Library Services to the Spanish-speaking, and has served on several ALA Presidential Program planning committees.
His publications include several books and numerous articles in the field of library science, bibliography, and in archives. His latest edited books include Latino Librarianship: A Handbook for Professionals (McFarland, 1990), Latino Periodicals: A Selection Guide (McFarland, 1998), Library Services to Latinos: an Anthology (McFarland, 2000), and, Pathways to Progress: Issues and Advances in Latino Librarianship (ABC-CLIO, 2011).
He is an active conference speaker and organizer on topics such as ethnic archives and manuscripts, library services to Latinos, library cultural diversity, community analysis, and digitizing for diversity. In addition to his academic writings he has written news commentaries on local public education topics.
He makes his home in Santa Barbara, California, with his wife Linda and his youngest son Alex.