stylistic:tone
Social structure

Citizen families were headed by the family's oldest male, the pater familias, who was lawfully entitled to exercise complete authority (patria potestas) over family property and all family members. Citizenship offered legal protection and rights, but citizens who offended Rome's traditional moral code could be declared infamous and lose certain legal and social privileges. Citizenship was also taxable, and undischarged debt was potentially a capital offence. A form of limited, theoretically voluntary slavery (debt bondage, or nexum) allowed wealthy creditors to negotiate payment of debt through bonded service. Poor, landless citizens of the lowest class (proletarii) might contract their sons to a creditor, patron or third party employer to obtain an income or pay off family debts. Nexum was abolished only when slave labour became more readily available, most notably during the Punic wars.

Slaves could be bought, sold, acquired through warfare, or born and raised in slavery. There were no legal limits on the slave-owner's power over them. A few slaves were freed by their owners, becoming freedmen and in some circumstances citizens too. This degree of social mobility was unusual in the ancient world but itself limited; for example, freedmen were seen as permanently tainted, and their children could not become magistrates. Freedmen could play notable roles in various crafts and trades, particularly those who had been manumitted by the upper classes. Freed slaves and the master who freed them retained certain legal and moral mutual obligations.

At the other extreme were the senatorial families of the landowning nobility, both patrician and plebeian, bound by shifting allegiances and mutual competition. A plebiscite of 218 forbade senators and their sons to engage in substantial trade or money-lending. A wealthy equestrian class emerged, not subject to the same trading constraints as senators.

One of Rome's fundamental social and economic institutions was the client-patron relationship; its obligations were largely moral and social rather than legal, but permeated society, including in politics.

Citizen men and citizen women were expected to marry, produce as many children as possible, and improve—or at worst, conserve—their family's wealth, fortune, and public profile. Marriage offered opportunities for political alliance and social advancement. Patricians usually married in a form known as confarreatio, which transferred the bride from her father's legal control (manus) to that of her husband. Patrician status could be inherited only through birth; an early law, introduced by the reactionary Decemviri but rescinded in 445, sought to prevent marriages between patricians and plebeians. Among ordinary plebeians, different marriage forms offered married women considerable more freedom than their patrician counterparts, until manus marriage was replaced by free marriage, in which the wife remained under her absent father's legal authority, not her husband's. Infant mortality was high. Towards the end of the Republic, the birthrate began to fall among the elite. Some wealthy, childless citizens resorted to adoption to provide male heirs for their estates and to forge political alliances. Adoption was subject to the senate's approval.