Endogamy is not a salient feature of Igbo marriage institutions, except to the extend that a special class of ritual slaves, the osu, and people of free status, dyala, are prohibited from intermarrying. The traditional social order also included a wider category of domestic slaves, who regularly intermarried with people of dyala status. In addition special statuses are attributed to the children of men who had acquired prestigious "yam titles". The son of such a man is supposed to marry a first wife whose father has also taken a yam title and may not include any other women of the same status in later marriages. This in-marriage pattern does not generate a closed group as such. A son may be given a special status because of his father's efforts, but he does not actually inherit the title, and, accordingly, his own son will not be obligated to marry in a specific way.
Specific marriage choices and arrangements are generally organized by the couple's parents, and betrothal was traditionally arranged when each intended partner was still a child or even at birth. Relationships, exchanges, and alliances between the prospective affines formed the main points of the marriage decision. Bride wealth payments of substantial value were and still are necessary features of all recognized marriages and are necessary to establish any children of the union as their father's descendants and members of his patrilineage. Paternity as such derives from this transaction rather than the biological act of conception. If a woman has children before she is married, they become members of her patrilineal group. If she becomes pregnant because of an extra-marital affair, the baby is still considered to be her legal husband's child. Similarly, in the Igbo practice of "woman marriage", a woman who has paid the bride price for another woman becomes her legal husband and retains the right of claiming any issue as her own.
As in many other West African cultures, bride payments are made in cash rather than in the form of special valuables. A husband will receive help in acquiring the necessary amount from his father, especially for a first marriage. The sum is determined by negotiations between the two families involved, although a fairly standard sum is usually approximated. It is divided into installments. The first is advanced at betrothal. The second is made when the bride moves into the husband's compound, usually under the care of her new mother-in-law. The last and most substantial payment occurs when the formal marriage ceremony takes place. However, the negotiated sum is never really paid in full, and in-laws may continue to make monetary and service demands through the life of their son-in-law. Among other functions, this aspect of the custom maintains the importance of affinal relationships.
Upon receipt, the main bride payment is divided between a girl's mother and father. The former will usually use the funds to buy household goods to provision the new household. The latter will use his receipts to acquire an additional wife for himself or a first wife for a son. Thus, even though it is valued in terms of a generalized currency, bride wealth tends to circulate within a contained sphere of transaction. Some provision must be made for the possibility that the fund must be reimbursed if a daughter becomes divorced or does not produce children for her husband. This possibility, of course, gives the bride's parents a vested interest in the stability of her marriage and encourages them to help settle any marital difficulties. If a man dies, his wives are inherited by the brother who succeeds him. A son may alternatively inherit, but, of course, will not become married to his own mother.
When a new bride is introduced into her husband's village, she resides in her mother-in-law's hut and is placed under her authority. However, if she is a second or subsequent wife she may be assigned to a senior co-wife. At the time that she begins to have children, she is assigned a hut of her own. Her husband will maintain a room of his own, especially if he has other wives, and each wife will be responsible for providing for their own children from their own efforts and from resources and income provided by the male householder. A woman's efforts are divided between farm and other domestic production that is undertaken by the compound as a whole and other economic activities that a woman and her children carry out on their own account. In this arrangement, any income that a woman earns by herself can be used at her own discretion without her husband's advice or approval. General governance within the compound involves male control in theory, but practical day-to-day domestic management is allocated to the women. Senior generations assume authority over junior ones and senior wives, in order of marriage, take precedence over their juniors. Women born from the house, i.e., sisters, when they are present, rank above wives.
As intimated above, the traditional Igbo social order is fundamentally based on polygyny and, prior to the influence of Western culture, most men aimed for and attained control over several wives. Large households with many wives and children established the social foundation for a man to assume the prestigious status of "big compound head" and the economic basis for controlling a substantial productive operation. With these assets, a man establishes himself as a key member and important leader within his community. As in other polygynous systems, status tends to correlate with age. Younger men require a long time to amass the necessary bride wealth or to obtain it from their fathers and form a cohort of bachelors in their twenties. Older men acquire several wives in the course of their lifetimes. The correlation between polygyny and status is also expressed in women's social careers. They can acquire wives on their own account and become female husbands if they pay the requisite bride price. The incentive to do so may be infertility and their obligation to their own husbands to provide heirs. In this situation a woman will use her own resources to acquire a co-wife and claim any of her children as her own. Alternatively, a woman, especially if she is very wealthy, will set up her own compound and take wives to establish and advance her own status. In this case the wives involved will have affairs, sometimes with men of the "husband's choosing, and add any children as dependents of her household. They will accordingly form a minor lineage of which she is the founder. Although this group has a female ancestor, subsequent descent will be traced through her sons and subsequent male offspring to form a patrilineal group.