Nader’s areas of interest include comparative ethnography of law and dispute resolution, conflict, comparative family organization, the anthropology of professional mindsets and ethnology of the Middle East, Mexico, Latin America and the contemporary United States. She was involved in conferences in the 1960s, determining the direction the study of law in society as a part of society and not insulated and isolated from other human institutions, should take as it developed. Nader edited and published essays from these conferences as well as authoring several books on the anthropology of law, establishing herself as one of the most influential figures in the development of the field.

Some of her work focuses on conflict resolution in the Zapotec village she studied. Nader notes that people confront each other face to face on a personal scale. Judges strive to find solutions that are balanced rather than placing one hundred percent of the blame on one party. Nader believes this reflects the society, their economic system, hierarchal structure and any other institution or variable. In contrast, she finds that in the United States, conflict often escalates to polarized blame and violence. The group of people a person may need to confront may be large and impersonal and much more powerful than themselves. She concludes that the kinds of cases people bring to court, reflect areas of stress in the social structure of a community.

However, Nader has written extensively about "harmony ideology," the ideology centered around the belief that the existence of conflict is necessarily a bad or dysfunctional thing and that a healthy society is one that achieves harmony between people and minimizes conflict and confrontation. She has argued in her book Harmony Ideology that harmony ideology has been spread amongst colonized peoples around the world by missionaries prior to (and facilitating) their military colonization and that the Zapotec used it in a "counter-hegemonic" way by maintaining the appearance of harmony (while in practice engaging in a great deal of litigation) in order to prevent the Mexican government from interfering with their relative autonomy. Nader has also argued that harmony ideology has been an important basis for unsubstantiated ideas that have developed in the United States since the 1960s about a "litigation explosion" and for the development of Alternative Dispute Resolution (ADR) as a method for removing so-called "garbage cases" (for instance, the then newly appearing civil rights cases of the 1960s) from the courtroom into an arena that emphasizes harmony, compromise and the language of therapy over talk of injustice.

While Nader's career began with a strong interest in law and forms of social control, over time she became more interested in questions of cultural control and "controlling processes" (also the title of an immensely popular undergraduate course she teaches), a concept described further in her 1997 article, "Controlling Processes: Tracing the Dynamic Components of Power."

One of Nader's best known contributions was in writing the at the time highly controversial "Up the Anthropologist--Perspectives Gained From Studying Up" in 1969, which was "one of the first calls to anthropologists to think more about the 'study of the colonizers rather than the colonized, the culture of power rather than the culture of the powerless, the culture of affluence rather than the culture of poverty.'" This call led many anthropologists to begin to "study up," although many misinterpreted Nader's call and did not simultaneously study "down" and "sideways." Nader's works for the field of anthropology and discipline have led her to be described as "the embodied moral conscience of post-Boas American anthropology."

Nader has coined the term "trustanoia" to describe the antonym of paranoia and the state of Americans' feeling of trust of others. She contends that people in the United States trust that there is always someone there to take care of them, and that everyone (including legislators and politicians) acts in their interest.

Books

• . Reprinted in 1996 , 2002 and 2005 .
• Reprinted in 2005 ISBN 0520231635.
• Printed in 2008 ISBN 9781405178945.