Pinpointing the challenging aspects of academic language for young adolescent English-language learners and English-only students

As students transition from elementary to middle school, they are expected to learn from content-area texts that are not only conceptually dense but also are more linguistically complex than those they encountered during the primary years. Many students in US schools, however, have not adequately developed the ability to comprehend and produce such academic texts. One source of difficulty is that many linguistic features of these texts---features that are characteristic of academic language---are unfamiliar to them. This dissertation investigates how students' understanding and use of these linguistic features play a role in the reading comprehension and academic writing of English language learners (ELLs) from Spanish-speaking backgrounds and English-only (EO) students in fifth grade.;Two empirical studies and one integrative piece addressing the implications of this thesis are presented. The first study explored whether knowledge of one feature of academic language---understanding of connectives (e.g., although, meanwhile)---explains variance in reading comprehension over and above vocabulary knowledge and word reading skills. Seventy-five ELL and 75 EO fifth graders were administered standardized tasks of vocabulary, word reading, listening and reading comprehension, and a researcher-designed connectives task.;The second study addresses a gap in the research on academic writing by documenting whether and how ELL and EO students employ features of academic language in writing. Narrative and persuasive writing samples (n=132) produced by 33 ELL and 33 EO students were coded for presence of academic vocabulary, unique words, connectives, lexical density, and embedded clauses.;These studies produced three major findings that enrich our understanding of those features of academic language that influence the reading comprehension and academic writing of ELL and EO students in early adolescence. First, knowledge of connectives plays a unique role in reading comprehension and therefore constitutes a specific subdomain of vocabulary that contributes crucially to comprehension for all students. The second major finding qualifies the first: ELLS with a strong understanding of connectives are less likely to leverage this knowledge for comprehension. Finally, ELL and EO students employ the academic language features with similar frequency in narrative and persuasive writing, with notable differences emerging only between genres.