This chapter presents the evolution of provisions on the capacity to do legal acts in effect in the Polish lands since the partitions of Poland, preceded by some observations on how the issue was regulated in pre-partition Poland. It is worth remembering that a clear distinction between legal capacity and the capacity to do legal acts had been developing in the legal theory for a long time, and it was not until the beginning of the 20th century, owing to the German Civil Code BGB, that it was popularised. An important part of these deliberations is a description of the regulations on the protection of one of the parties to a relation under civil law due to the non-equivalence of performances, resulting in the detriment to the vulnerable party. Polish pre-partition private law was of customary nature and was not codified. The resolutions (constitutions) of the parliamentary assembly (Sejm) only slightly modified the customary nature of the law.