Analyzing the data of Columella's treatise and the works of Roman jurists of the classical period the author comes to the following conclusions. Management of an agricultural estate could imply existence of three types of slave managers. Organization of production and labour force was controlled by administrating managers (vilicus and vilica); connections between the estate and other economic units (selling the harvest and hiring workers) were in the competence of a business manager (institor agris colendis praepositus, condendis vendendisque frugibus praepositus); accounts were kept by a financial manager (actor). The last function would often be combined with the first one and performed by vilicus, while the functions of institores were usually fuflilled by a procurator, a freedman. Organization of production in the estate was under the control of vilicus and vilica working in a well co-ordinated co-operation based upon a division of labour according to the following directions: organizing work immediately in the field and at the villa, overseeing the slaves, controlling their state of the labour force and controlling the state of agricultural implements. Usually a vilicus was not in charge of selling the harvest or hiring workers, and he would only occasionally act at the market. His duties did not imply concluding bargains and other business activities: he was entirely engaged in organizing production in the estate. Because of his praepositio, a vilicus, unlike an institor, had no right to oblige his master in solidum. Vilicus was not an institor and could not oblige his master by actio institoria. When a vilicus concluded a bargain, the best way for the contractor to make the landowner responsible was actio de in rem verso. The legal status of an actor was much the same. On the contrary, the duties of institor, who could be appointed manager of the estate (institor agris colendis praepositus, condendis vendendisque frugibus praepositus), included concluding bargains, which implied the landowner's responsibility in solidum connected with actio institoria. Thus, the legal status of a slave manager depended directly on the character of his economic activities.