<p>The present paper investigates the issue of stability of self-knowledge with an emphasis on its particular category referred to as self-standards. We considered four types of self-standards (i.e. the ideal self, the ought self, the undesired self, and the forbidden self) and two aspects of their stability. First, we analysed changes in the content of attributes used to describe each of the four self-standards. The second aspect was the stability of beliefs related to actualization (ACT, which is conceptually close to a concept of self-discrepancy) of those standards. In a series of three studies we explored the stability of self-standards independently in adults (studies 1 &amp; 2), adolescents (study 2) and older adults (study 3). In all studies we measured self-standards (their contents and related ACT beliefs) two times (test-retest) using the SSM (Self-Standards’ Measure) procedure. In study 3, some modifications of the SSM were applied to make it appropriate for measurement in older adults. We found the moderate level of the content aspect of stability. Regarding the stability of ACT beliefs, we found a consistent pattern of results indicating relatively higher stability of beliefs related to the ought self as compared to all other three types of self-standards. In addition, the stability of the content of attributes used to describe self-standards turned out to be generally unrelated to the stability of beliefs regarding the actualization of self-standards. This research has potential implications for theories of self-knowledge and the role of self-standards in dynamics of self-regulation. </p>