The analysis of age-specific developmental crises is based upon L. S. Vygotsky's general notions in D. B. El'konin's interpretation. Initial premises concerning real and ideal developmental forms are applied to basic psychological structures such as activity at will, generalization of experience, accordance to regulations. Stratification of transition period is presented. Crucial phase is formed by three stages: mythologization of ideal form, conflict and reflection. As a result a new structure differential self-evaluation comes into existence.