The experiences in close relationships revised (ECR-R) is widely used to assess romantic attachment dimensions. Investigating cultural limitations in its applicability is imperative. This study aims to examine the instrument’s: (1) factor structure in two large and normative samples of Greek (N = 1706, M age = 16.16; SD = 2.16; 49.7% male) and Cypriot (N = 1279; M age = 15.54; SD = 0.65; 44.9% male) adolescents; (2) measurement invariance between these groups, accounting for potential gender and age effects. Results supported the two-factor structure and indicated partial invariance of the constructs between Greek and Cypriot adolescents. Findings support limitations in the use of instruments adapted for Greece in Cyprus.