Language attrition, the reverse process of acquisition, is part of the field of language acquisition, and vocabulary is the first and most frequent linguistic unit that suffers attrition. Vocabulary attrition of young L2 learners deserves special attention because a successful language learning experience at the early stage facilitates learners’ later learning efficiency. However, research on young L2 learners’ vocabulary attrition seem scant in the current literature. Such being the case, this study investigates 72 Chinese primary school EFL learners’ English vocabulary attrition after an interval of a two-month summer recess through a repeated vocabulary test. Statistical results indicate that the young Chinese learners suffer significant attrition in vocabulary after the disuse of English during the holiday. In addition, verbs are found to be more vulnerable than nouns to attrition, but many words are partially remembered instead of being completely forgotten, as Retrieval Hypothesis proposed. Pedagogical implications for vocabulary teaching in Chinese primary schools and other similar L2 contexts are discussed.

We examined the linguistic features of texts in twenty-nine picture books used in an early English as a Foreign Language program in China. We used the software CLAN to automatically extract indices of linguistic complexity that are typically used to analyze child-directed speech and tested if these indices aligned with expert judgments on the books’ appropriate grade level (Kindergarten-1 through Kindergarten-3). Of the eleven characteristics investigated, seven showed significant between-level differences with moderate effect sizes. Across all levels, vocabulary complexity (i.e., frequency of types, frequency of tokens, and vocabulary diversity) and syntactic complexity (i.e., number of verbs per utterance, number of Developmental-Sentence-Scoring-eligible utterances, mean length of utterance in morphemes, and total number of non-zero morphemes) increased, also in alignment with experts’ judgments. Indices of child language development can thus be used to estimate text complexity in picture books. The study contributes to a better understanding of children’s picture book difficulty and has methodological implications for investigating text characteristics for very young children learning English as a foreign language.