Background <p>The Existence, Relatedness, and Growth (ERG) theory provides a framework for understanding employee motivation. However, the psychometric properties of the ERG scale have not been thoroughly examined within the context of Indonesian Generation Z employees, and key theoretical debates regarding the simultaneity of needs and frustration-regression mechanisms remain unexplored in relation to expected measurement structures.</p> Methods <p>A cross-sectional survey was conducted among 751 Indonesian Generation Z employees (born between 1997 and 2008) recruited through professional networks, social media platforms, and organizational contacts across multiple industries. The ERG scale was translated and culturally adapted using forward-backward translation procedures and cognitive interviews with Gen Z employees. This study employs the Item Response Theory (IRT) framework, specifically Rasch analysis, to validate the instrument’s psychometric properties. Confirmatory Factor Analysis (CFA), network analysis, and Rasch modeling were used to examine factorial validity, reliability, convergent and discriminant validity, and measurement invariance across gender.</p> Results <p>CFA confirmed the theoretically-derived five-factor structure (differentiating Existence into Pay and Fringe Benefits, Relatedness into Superiors and Peers, alongside Growth) with excellent fit indices (CFI = 0.994, TLI = 0.993, RMSEA = 0.069). Network analysis revealed clear clustering of items according to theoretical domains. Rasch analysis, grounded in Item Response Theory, indicated that the items fit well and were reliable, with item difficulties concentrated at or below 0 logits, indicating optimal measurement precision for low to moderate levels of need satisfaction while suggesting potential ceiling effects for highly satisfied individuals. Measurement invariance was established across gender groups. Convergent and discriminant validity were demonstrated through theoretically meaningful correlations with job satisfaction (<i>r</i> = 0.418–0.700) and self-esteem (<i>r</i> = 0.047–0.179), with all correlations below <i>r</i> = 0.85 supporting discriminant validity.</p> Conclusions <p>The Indonesian version of the ERG scale is a valid and reliable instrument for assessing motivational needs among Generation Z employees. The scale demonstrates particular utility for identifying specific need deficits in low to moderate satisfaction ranges and can inform targeted organizational strategies for employee engagement and retention.</p>