The central theme of ethnic nationalists is that "nations are defined by a shared heritage, which usually includes a common language, a common faith, and a common ethnic ancestry". It also includes ideas of a culture shared between members of the group, and with their ancestors. However, it is different from a purely cultural definition of "the nation", which allows people to become members of a nation by cultural assimilation; and from a purely linguistic definition, according to which "the nation" consists of all speakers of a specific language.
Herodotus is the first who stated the main characteristics of ethnicity, with his famous account of what defines Greek identity. He lists kinship (Greek: ομόαιμον, homόaimon, "of the same blood"), language (Greek: ὁμόγλωσσον, homoglōsson, "speaking the same language"), cults and customs (Greek: ὁμότροπον, homόtropon, "of the same habits or life").
The outcome of this right to self-determination may vary, from calls for self-regulated administrative bodies within an already-established society, to an autonomous entity separate from that society, to a sovereign state removed from that society. In international relations, it also leads to policies and movements for irredentism to claim a common nation based upon ethnicity.
In scholarly literature, ethnic nationalism is usually contrasted with civic nationalism. Ethnic nationalism bases membership of the nation on descent or heredity, often articulated in terms of common blood or kinship, rather than on political membership. Hence, nation-states with strong traditions of ethnic nationalism tend to define nationality or citizenship by jus sanguinis (the law of blood, descent from a person of that nationality), and countries with strong traditions of civic nationalism tend to define nationality or citizenship by jus soli (the law of soil, birth within the nation state). Ethnic nationalism is, therefore, seen as exclusive, while civic nationalism tends to be inclusive. Rather than allegiance to common civic ideals and cultural traditions, then, ethnic nationalism tends to emphasise narratives of common descent.
The theorist Anthony D. Smith uses the term "ethnic nationalism" for non-Western concepts of nationalism as opposed to Western views of a nation defined by its geographical territory. Diaspora studies scholars extend this non-geographically bound concept of "nation" among diasporic communities, at times using the term ethnonation or ethnonationalism to describe a conceptual collective of dispersed ethnics.
Ethnic nationalism is also present in many states' immigration policies in the form of repatriation laws. States such as Armenia, Bulgaria, Croatia, Estonia, Finland, Germany, Greece, Hungary, Ireland, Israel, Italy, Malaysia, Romania, Russia, Serbia, and Turkey provide automatic or rapid citizenship to members of diasporas of their own dominant ethnic group, if desired.
In Malaysia, the Bumiputera principle recognises the "special position" of the Malays provided in the Constitution of Malaysia, in particular Article 153. However, the constitution does not use the term bumiputra; it defines only "Malay" and "indigenous peoples" (Article 160(2)), "natives" of Sarawak (161A(6)(a)), and "natives" of Sabah (Article 161A(6) (b)). Certain but not all pro-bumiputra policies exist as affirmative action for bumiputras, for NEP is racial-based and not deprivation-based. For instance, all Bumiputra, regardless of their financial standing, are entitled 7 percent discount on houses or property, including luxurious units; whilst a low-income non-Bumiputra receives no such financial assistance. Other preferential policies include quotas for the following: admission to government educational institutions, qualification for public scholarships, marking of universities exam papers, special bumiputras-only classes prior to university's end of term exams, for positions in government, and ownership of businesses. Most of the policies were established in the Malaysian New Economic Policy (NEP) period. Many policies focus on trying to achieve a bumiputra share of corporate equity, comprising at least 30% of the total. Ismail Abdul Rahman proposed this target after the government was unable to agree on a suitable policy goal.
In German nationality law, citizenship is open to ethnic Germans. According to the Greek nationality law, Greeks born abroad may transmit citizenship to their children from generation to generation indefinitely. As of 2013 this is also true in the case of the Philippine nationality law which, has conferred Philippine citizenship on children born after 15 October 1986, with at least one Philippine citizen parent.
On the other hand, civic nationalism defines membership as an individual's duty to observe given laws and in turn receive legal privileges.
A nation-state for the ethnic group derives political legitimacy from its status as homeland of that ethnic group, from its protective function against colonization, persecution, or racism, and from its claim to facilitate the shared cultural and social life, which may not have been possible under the ethnic group's previous status as an ethnic minority.