Abstract: The subject of the research is the contact boundaries between Self and not-Self as the 'between space' where personality dispositions are formed and transformed in terms of Self and not-Self interactions. The purpose of this research is to analyze and systematize characteristics of Self boundaries that change as a result of contact with not-Self and determine personality transformations. The author of the article pays special attention to clarifying the content and connections between Self and non-Self phenomena in terms of their multiplicity and description of their contact boundaries as well as deficit thereof and ways to overcome it. The article is based on the interdisciplinary and nomothetic approaches. The author has also used the  problem method to state, analyse and interpret unsolved problems that do not have a single research approach today. Analysis, evaluation, summary and amendment of a number of well-known psychological concepts and provisions are based on the axiomatical method. The novelty of the research is caused by the fact that the author proves that there are internal cause-and-effect relationships between characteristics and changes in contact boundaries between Self and not-Self and personality transformations. The main conclusions of the research are the following: 1) there are certain contact boundaries between Self and not-Self as personality disposition forming and transforming phenomena, and 2) boundary characteristics play an important role in changing these boundaries as well as creating constructive or destructive potentials of these changes and connections between Self and not-Self contact boundaries and personality disposition transformations.