In the study of social structure in the Roman world of the first and second centuries ad nothing is more important or more complex than the slave and freed slave classes. Their numbers, although not absolutely determinable, were large and even predominant in many urban and some rural areas. Most urban slaves of average intelligence and application had a reasonable expectation of early manumission and often of continued association with their patron. They enjoyed a high rate of social advancement, which was often much greater than that of the freeborn proletariate. The fundamental social legislation of Augustus attempted to provide a stable social hierarchy based on legal status. But, at the same time, there was in the early Imperial period a degree of social mobility sufficient to prevent the structure breaking down in violence and social discontent. Among the mobile sections of society the slave-born classes played a significant role.

But the status ladder within these classes themselves is both long and complex. From the point of view of juridical status, there is not only the fundamental distinction between slaves (servi) who are without rights, and freed slaves or freedmen (liberti) who are citizens, but there are also further distinctions within each of these classes – formally manumitted freedmen with full citizenship, informally manumitted freedmen (Latini Iuniani) who did not acquire Roman citizenship, but only Latin status without full political rights, and dediticii who could never become Roman citizens.