This study tests the Fundamental Difference Hypothesis, which suggests that adults rely on explicit, problem-solving mechanisms for second language (L2) acquisition, while children use implicit mechanisms. The hypothesis predicts that only adults with high verbal analytical ability will achieve near-native L2 competence, but that verbal ability is not a significant predictor for childhood acquisition. The study confirms this by showing that few adult Hungarian immigrants scored within the range of child arrivals on a grammaticality judgment test, and that those who did had high verbal ability. This supports Johnson and Newport's (1989) findings that L2 proficiency declines with age, but that exceptions may be explained by explicit learning mechanisms. The study also challenges the Critical Period Hypothesis, suggesting that age effects may not be exceptions if the hypothesis applies only to implicit learning. The findings indicate that adults with high verbal ability can achieve near-native competence, but that this ability is not a significant predictor for children. The study also highlights the role of verbal aptitude in L2 acquisition, showing that high aptitude learners perform better, especially in complex grammatical structures. The results suggest that while age affects L2 acquisition, verbal ability plays a crucial role in adult learners. The study's findings support the Fundamental Difference Hypothesis, showing that adults with high verbal ability can achieve near-native competence, but that this ability is not a significant predictor for children. The study also shows that different grammatical structures are affected differently by age, with some structures showing strong correlations and others not. Overall, the study confirms that age has a significant impact on L2 acquisition, but that verbal ability is a key factor in adult learners' success.This study tests the Fundamental Difference Hypothesis, which suggests that adults rely on explicit, problem-solving mechanisms for second language (L2) acquisition, while children use implicit mechanisms. The hypothesis predicts that only adults with high verbal analytical ability will achieve near-native L2 competence, but that verbal ability is not a significant predictor for childhood acquisition. The study confirms this by showing that few adult Hungarian immigrants scored within the range of child arrivals on a grammaticality judgment test, and that those who did had high verbal ability. This supports Johnson and Newport's (1989) findings that L2 proficiency declines with age, but that exceptions may be explained by explicit learning mechanisms. The study also challenges the Critical Period Hypothesis, suggesting that age effects may not be exceptions if the hypothesis applies only to implicit learning. The findings indicate that adults with high verbal ability can achieve near-native competence, but that this ability is not a significant predictor for children. The study also highlights the role of verbal aptitude in L2 acquisition, showing that high aptitude learners perform better, especially in complex grammatical structures. The results suggest that while age affects L2 acquisition, verbal ability plays a crucial role in adult learners. The study's findings support the Fundamental Difference Hypothesis, showing that adults with high verbal ability can achieve near-native competence, but that this ability is not a significant predictor for children. The study also shows that different grammatical structures are affected differently by age, with some structures showing strong correlations and others not. Overall, the study confirms that age has a significant impact on L2 acquisition, but that verbal ability is a key factor in adult learners' success.