Societas (social contract, partnership) is a consensual contract in Roman law concluded for the purpose of achieving a common goal of the members. The agreement of will (consensus), by which it is formed, is based on the principle of bona fides (good faith). Societas is a bilaterally binding contract with basically equal rights and duties of the members, who are called socii (partners). They pool their property or labor, or both, to achieve a common, legally permissible goal. In the era of the Roman Empire, societas was very widely used and the result was the development of four types of this contract. Its lucrative nature is common to all species, which is why it gains its full momentum simultaneously with the development of the economy, goods and money circulation, as trade as well. In addition to the economic, societas also has a social-ethical dimension because this form of community, in ancient times, was based on close, friendly and fraternal relations between members (partners), and these relations rested on the principles of solidarity and mutual trust. This contract has not been substantially changed to this day, moreover, it has progressively developed in accordance with modern circumstances, from ancient Greece, Babylon and the Roman Empire, through the Austro-Hungarian Monarchy, and - despite the legal vacuum during the Yugoslav communist rule - up to the present day Croatian law.