The "5 Cs of PYD Model" is an influential theory involving the role of Intentional Self-Regulation (ISR) in positive youth development (PYD). The model, which was developed with U.S. populations, has recently been used in other cultural contexts and, as such, the measurement invariance of the ISR-PYD model across cultural contexts must be assessed. This study examined whether the ISR-PYD model is conceptually similar across two cultures, the U.S. and Iceland. Participants were 2,473 U.S. and 539 Icelandic adolescents (65% female, 15.00 years; 46% female, 14.30 years, respectively). Results suggested weak invariance and partial strong invariance for PYD and partial weak invariance across groups and time for ISR. Bifactor modeling showed that ISR was more strongly associated with global PYD than individual Cs. These findings demonstrate construct validity of the ISR-PYD model, suggesting that ISR is a central asset in general healthy functioning among youth in different Western cultural contexts.