Transfer plays an important role in all forms of learning. The author distinguishes specific and unspecific, positive and negative transfer. On the basis of latest researches he analyses various kinds of transfer, especially from the viewpoint of relation tips between problems (assignments). Transfer arises either on the basis of similarity of elements and relations in a problem structure or on the basis of the sameness of processes and methods used in solving problems. In analysing the question of isomorphism of problem structures (the so-called mass problem) the author makes use of his own researches. He considers transfer as a generalized form of coding information, which leads to the creation of a cognitive learning-set. He is aiming at a theoretical synthesis of cognitivist viewpoints with the research results obtained on the basis of neo-behaviourist assumptions. He analyses questions of pre-differentiation, fixation, transfer in memory assignments etc. He gives a classified survey of the working of transfer in practical activities (in classroom learning and teaching, in vocational training and creative work). He points out that specific exercises lead to a generalized transfer as well as to generalized skills and bring on a cognitive learning set.