This document discusses dual language development in three key areas:
1. It outlines how children acquire their first language (L1) quickly in the first 5 years of life, learning phonology, lexicon, syntax, morphology, and communicative competence.
2. It defines dual language learners as either simultaneous bilinguals who acquire L1 and L2 together from birth, or sequential bilinguals who acquire L2 after establishing L1, typically after age 3.
3. Success in dual language development depends on linguistic, psychological, and social factors, such as the similarity of languages, quality of input, age and motivation of the learner, and the status and support of L1 and L2 in