Due to the increase in international trade, mass transportation, and information technology, the role of English as a global language has changed, and conventional EFL/ESL motivation needs paradigmatic reconstruction. This study compares Dörnyei’s (2009) recent proposal of a second language (L2) motivat-ional self-system with Gardner’s (1985) socio-educational model by investigating 2,832 Korean students’ English learning motivation from Grades 3 through 12 in 14 different schools. The cross-grade survey results indicated that Korean EFL learners’ motivational intensity showed a curvilinear pattern, which means their motivation consistently decreased until Grade 9 but increased from Grades 10 to 12. A series of regression analyses showed that Dörnyei’s L2 motivational self-system was a better predictor than Gardner’s socio-educational model in terms of the explanatory power for students’ English proficiency; students’ ideal L2 and ought-to L2 selves explained better than integrativeness and two types of instrumentality (i.e., promotion- and prevention-based). This confirms the findings of recent literature conducted in different nations. Also, the study provides empirical evidence that the ought-to L2 self, which is an external, social form of L2 motivation, functions only at the cognitive level, whereas the ideal L2 self, a more internalized form, taps into both the cognitive and affective levels.