Eritrean nationality law is regulated by the Constitution of Eritrea, as amended; the Eritrean Nationality Proclamation, and its revisions; and various international agreements to which the country is a signatory. These laws determine who is, or is eligible to be, a national of Eritrea. The legal means to acquire nationality, formal legal membership in a nation, differ from the domestic relationship of rights and obligations between a national and the nation, known as citizenship. Nationality describes the relationship of an individual to the state under international law, whereas citizenship is the domestic relationship of an individual and the nation. Eritrean nationality is typically obtained under the principle of jus soli, i.e. by birth in Eritrea, or jus sanguinis, born to a mother or a father of Eritrean origin or parents who came to Eritrea before 1934. It can be granted to persons with an affiliation to the country, or to a permanent resident who has lived in the country for a given period of time through naturalization.

Acquisition of nationality Nationality can be acquired in Eritrea at birth or later in life through naturalization.

By birth Those who acquire nationality at birth include:

Children born anywhere who have at least one parent who is an Eritrean national; or Abandoned children or orphans discovered in the territory whose parents are unknown.

By naturalization Naturalization can be granted to persons who have resided in the territory for a sufficient period of time to confirm they understand one of the languages used in Eritrea, customs and traditions of the society. General provisions are that applicants have good character and conduct; have no criminal convictions; have good mental and physical health without disabilities; can economically be self-sufficient; and did not act against the independence movement. After 1974, applicants must have resided in the country for twenty years, with breaks in residency allowed and prior to 1974, have continuously resided there for ten years. Besides foreigners meeting the criteria, other persons who may be naturalized include:

The spouse of an Eritrean national after a three-year residency period subsequent to the marriage; Adoptees whose parents are Eritrean can choose to acquire nationality; Minor children can be automatically naturalized when their parent acquires nationality; People who descend from a person who came in Eritrea before 1934 are indigenous of Eritrea People who resided in Eritrea between 1934 and 1951 are naturalized eritreans, if they were not involved in activities that were against the independence movement.

Loss of nationality Eritrean nationals can renounce their nationality pending approval by the state. Nationals may be denaturalized in Eritrea for acquiring dual nationality (other than by birth) or serving in the military of another state without government authorization; performing actions against state interests; performing actions indicating one is a national of another state; committing serious crimes, disloyal acts, or crimes against the state or state security; or for fraud, misrepresentation, or concealment in a naturalization petition. Persons who previously had other nationality but married and divorced an Eritrean, or attempted to repatriate to the nationality of their country of origin, may lose their nationality.

Dual nationality Dual nationality is typically allowed in Eritrea since 1992. Those who had dual status prior to independence require authorization from the government. Those who are born with dual nationality since independence may keep their nationalities, but those who are naturalized are required to renounce other nationality. Persons who serve as president must be born as nationals of Eritrea.

History Ottoman period (1557–1869) From the eighth century, five kingdoms of the Beja people — Baqlin, Bazin, Jarin, Naqis and Qata — stretched from Northeastern Sudan through the Tigray Province of Ethiopia. Rivalry between them led to a continuous state of conflict and decline, allowing the expansion of the Ottoman Empire along the coastline of the Red Sea to gain a foothold in 1517 and consolidate their rule in the Ḥabeş Province by 1557. Establishing a colonial power in what would become Eritrea, the Ottomans imposed their rule for the next 300 years. The western part of the territory of what is now Eritrea was part of the Funj Sultanate, which arose in 1504 and surrendered to the Ottoman Empire's Egyptian Province, in 1821. Within the Ottoman Empire, for six centuries, there was an internal organization that defined government functions for subjects by balancing religious and communal ties, weighing aptitudes and occupations without a centralized national ideology. Ottoman subjecthood was strongly tied to religion and non-Muslims, if they were ahl al-Kitāb (People of the Book), meaning Jewish, Christian, or Zoroastrian, could benefit from being subjects by agreeing to pay a tax to the sultan. Under a pact known as zimma, in exchange for paying taxes, the sultan allowed these subjects freedom of religion and guaranteed their lives, property, and rights with an understanding that they were legally entitled to less status than Muslim subjects. The pact was agreed to by the leaders of the confessional community, who managed the adherents and their internal organization under the religious law of their community.

By the eighteenth century a political organization, known as the millet, managed the affairs of their respective religious communities and developed into the protégé system (, protected persons). Signing treaties with European powers, from the 1673 signing of a Capitulation with France, the Ottoman Empire granted France control of certain Ottoman Christians, Austria control of some Ottoman Roman Catholics, most favoured nation status to British and Dutch traders, as well as specific rights to the Republic of Venice and Russian Empire. Under the terms of these treaties, foreign powers could recruit Ottoman subjects to serve their needs as commercial agents, consuls, or interpreters, and extend to these protégés diplomatic immunity from prosecution and privileges of trade, including lowered customs tariffs.

Over time, abuses of the system led to a virtual monopoly of foreign trade by protégés, clandestine sales of letters patent (), and demands from foreign powers for protection to extend from individuals to entire communities. The influence on Ottoman subjects by European powers changed the perception of these minority groups in the empire, meaning that they were increasingly seen not as Ottoman subjects, but as resident aliens. In 1798, France and Britain's conflicts during the Napoleonic Wars extended into Egypt. France occupied the territory until 1801, when the French were defeated and Britain set about assisting the Ottoman Empire in regaining its sovereignty. To curb the disruptive effects of Europeans in the empire, from 1806, the Ottoman government began sending communiques to the foreign embassies demanding compliance with the terms of their agreements. Failing to achieve success diplomatically, in 1839, the Ottoman government issued the Edict of Gülhane, in an effort to end bribery and corruption, and to create fair tax schemes and institutions to protect the basic rights of Ottoman subjects. The Ottoman Reform Edict of 1856 () categorized subjects by whether they were Muslim or non-Muslim, granting different civil statuses to each. In 1863, new regulations upon protégés restricted the privileges they received in the empire and clarifying who were thereafter considered to be Ottoman subjects and who were foreigners.

To further define subjects of the Ottoman Empire, new nationality legislation was passed in 1869 (tâbiiyet-i osmaniye kanunnamesi, Ottoman Nationality Law). The law specified terms for the acquisition and loss of who was within the sovereignty of the empire, rather than the domestic obligations and rights of citizenship. It described who was a subject, owing allegiance, and made provisions for wives, children, emigrants and immigrants. Under its terms, children derived nationality from their fathers, foreigners born in the territory could acquire nationality at majority, and foreigners born elsewhere could obtain nationality after five years residency within the imperial realm. Specific provisions included that foundlings discovered within the territory; stateless persons living in the empire; Muslim women, who despite the ban on such marriages, had married Persian men and the children of such a union; unregistered persons who had not been counted in the Ottoman census, either because no census was taken or their births were unregistered, were all considered to be Ottoman. Foreign women acquired Ottoman nationality through marriage, but could return to their original nationality upon the death of their spouse. Nationality could also be granted based on special contribution or service to the nation. Dual nationality was permitted, but was discouraged, as the government could choose not to recognize naturalization of an Ottoman subject by another state.

When the Suez Canal opened in 1869, an Italian, Lazarist missionary Giuseppe Sapeto was hired to assist in securing a Red Sea port for Italy. Sapeto had first come to Eritrea in 1837 and worked in the Akele Guzai region. He later worked near Keren and was knowledgeable in the language and culture of the region. He acquired land on the Bay of Assab from local chiefs on behalf of the Rubatino Maritime Company, giving Italy a base from which to begin colonization and commercial expansion in the region. Conflict between Egypt and the Abyssinian Empire persisted throughout the 1870s, and in 1876, the northern highlands were annexed by Abyssinia's Yohannes IV. In 1879, the conflict ended and Britain attempted to broker a peace between Egypt and Abyssinia, but was unsuccessful. In 1882, the Italian government purchased the interests of the Rubatino Maritime Company to Assab. As Italian explorers began to widen their spheres of influence, disputes emerged with the Abyssinians. Attacks on an Italian settlement at Dogali in 1887, led to an invasion by Italian military forces. In 1889, Abyssinian Emperor Menelik II, recognized Italian claims and settled the borders of Eritrea by the Treaty of Wuchale.

Italian period (1889–1941) Official occupation by Italy began in 1889 and in 1890 the colony was formally named Italian Eritrea. Italian subjecthood was first declared during the Unification of Italy in 1861. As the states united, their former kingdoms and duchies ceased to exist and no alternative means of belonging had been devised. Thus, in March 1861 the former Savoy-Piedmont-Sardinia Kingdom officially proclaimed that the former Piedmontese subjecthood was extended to the entirety of Italy. Inhabitants were afforded protection based upon their allegiance to the monarchy. Subjecthood was derived from an Italian father, and could only be derived maternally if the father was unknown. Birth in the territory was treated differently in different areas; in some states it conferred subjecthood, and in others it did not. Naturalization and denaturalization processes also varied depending upon the province. In 1865 laws from the various states was codified into national legislation, including a new civil code, which went into force on 1 January 1866.