This book delves into psycholinguistic and cognitive aspects of lexical activation, availability, and production in English or Spanish as additional languages in classroom settings. Instead of focusing sociologically and pedagogically on lexical availability, this collective work adopts a cognitive approach. Ten studies, conducted by experienced researchers, employ a uniform methodology based on lexical availability tests in classroom contexts. Notably, each study permits learners to produce as many responses as possible within two minutes, revealing common associations and network patterns in lexical production. The book is innovative not only in providing cognitive data from Spanish learners of English, but also from Greek, Polish, and North American learners of Spanish, expanding the scope beyond traditional research on word associations. While acknowledging the pioneering work in word associations among French and English learners, this book distinguishes itself by using lexical availability tests to explore word associations and networks in the mental lexicon of English or Spanish learners in classroom contexts. Notably, it offers lexical data from children and adolescents learning English in primary or secondary schools, as well as Spanish learners in high school and university settings, filling a gap in research on younger learners and languages other than English. The book addresses the need for empirical data on the mental lexicon of English or Spanish learners, particularly in primary or secondary classrooms, a scarcely investigated educational context.