This chapter delves into the role of discourse in language development, extending beyond simple grammar to encompass social context and effective communication. It examines how cognitive structures, linguistic principles, and text genres – narrative, descriptive, expository, and argumentative – interact to shape discourse. Special focus is placed on cognitive discourse functions (CDFs), which guide thought and communication, alongside the importance of cohesion and coherence in constructing meaning.

While discourse is often overshadowed by syntax and lexis, research uncovers developmental patterns in both monolinguals and bilinguals. As learners advance, they refine cohesion strategies, transition from narrative to expository texts, and better integrate CDFs. Tools like Coh-Metrix and TAACO aid in discourse analysis, though much is still to be explored.

L1 and L2 discourse development follows similar paths, though L2 growth may lag due to syntactic proficiency thresholds. This chapter highlights the interplay of cognition, language exposure, and academic demands in shaping discourse mastery, reinforcing the need to support multilingual proficiency in education.

This chapter explores the role of syntax in language development, showing how sentence structure evolves in bilinguals. Early L2 learners rely on L1 syntax or imitation, gradually forming independent L2 structures. Over time, L1 and L2 syntax merge, creating shared language nodes. Research confirms that both grammar systems remain active during language use.

Syntactic complexity is key to proficiency, measured through indices like clause structure and subordination. Advances in computational tools, such as Coh-Metrix and L2 Syntactic Complexity Analyzer, allow automated analysis of syntax. Studies show that bilinguals develop longer sentences, longer and more complex noun phrases, and more subordinate clauses over time.

Children worldwide follow a natural syntax progression – juxtaposition first, subordination later, and nominalization at higher levels. Bilinguals display unique patterns, with advanced L2 learners favouring longer sentences, relative clauses, and passive structures. This chapter highlights syntax’s role in bilingual growth and its impact on proficiency assessment.

This chapter delves into the critical role of lexis in L1 and L2 acquisition, exploring how vocabulary reflects language development and impacts text quality. The mental lexicon forms an intricate web of semantic connections, with bilinguals processing words differently based on proficiency. Low-proficiency learners rely on L1 translation, while advanced speakers strengthen direct links to L2 vocabulary. Research shows that both languages remain active during lexical tasks, shaping bilingual cognition.

Lexical richness is analysed through key models, including Crossley’s and Jarvis’. Advances in natural language processing have enabled automated evaluation tools like Coh-Metrix and TAALES, enhancing lexical analysis.

As bilinguals progress, their writing becomes more diverse and sophisticated, though L1 and L2 development may diverge in features like word concreteness. Formulaic language is also crucial – high-proficiency L2 writers use more native-like phrasal structures. By examining lexical acquisition, this chapter highlights its significance in bilingual proficiency, providing insights into how vocabulary shapes linguistic competence.