The document discusses the concept of ultimate attainment in second language acquisition research. Ultimate attainment refers to the end state or final level of proficiency achieved by second language learners. The study of ultimate attainment provides insights into limitations on second language learning. While first language acquisition universally results in native-like competence, second language acquisition often leads to non-native like outcomes. Younger ages of second language acquisition are associated with higher levels of ultimate attainment. The end state may be incomplete or divergent from the target language. Access to Universal Grammar and differences between language pairs also influence ultimate attainment.