Second-language (L2) acquisition is generally thought to be constrained by maturational factors that circumscribe a critical period for native-like attainment. Consistent with the maturational view are age effects among learners who begin L2 acquisition prior to, but not after, closure of the putative critical period. Some studies indicate that native-like acquisition of a second language by learners after critical period rarely happens. Some subsequent studies do not support the critical period account of L2 acquisition constraints, however. Accordingly, this study was undertaken to investigate the impacts of maturational constraints on native-like attainment of second language accent, pronunciation, and intonation by Iranians who spent some years in English-speaking countries. The performance of 120 Iranian late and early arrivals was evaluated using a 6 point semantic differential scale. Descriptive and inferential statistics (independent sample t-test and ANOVA) were run (p≤ .05) to analyze the data. In keeping with other researchers, the results of the study indicate that L2 native-like attainment is constrained by the age of language learners. The results also indicate that late language learners who lived in an English-speaking country acquired near native-like proficiency whereas the late language learners who lived just in Iran were not able to acquire near native-like pronunciation. We also found modest evidence of native-like attainment among late learners.