The Existential Isolation Scale (EIS) aims to measure existential isolation through the assessment of I-sharing experiences. While the scale has been validated across multiple studies, questions remain about whether it fully captures the theoretical construct of existential isolation as conceptualized by Yalom. This study aimed to answer this question, validate its Russian adaptation, and examine its construct validity. Through three studies with different Russian samples (Study 1: N = 16 expert psychologists; Study 2: N = 177 undergraduate students; Study 3: N = 500 adults), we evaluated the scale’s psychometric properties and its relationship with other psychological constructs. For Study 3, we also split the sample into two groups of people: those who wanted to relocate or relocated and the rest. We assumed that the first group, due to the critical event of relocation, should be naturally “primed” and hence, experience higher levels of existential concerns. The results demonstrated good internal consistency (α > .8) and test–retest reliability (r = .73) of the EIS. Many expected correlations were found. However, the scale showed no meaningful correlation with existential anxiety (r = .15) and produced unexpected results when comparing groups experiencing potential existential crises during the critical event. These findings indicate that while the EIS reliably measures I-sharing experiences, it may not capture the broader construct of existential isolation, highlighting the need for more comprehensive measurement tools in existential psychology. (PsycInfo Database Record (c) 2025 APA, all rights reserved)