Seven Stages of Language Functioning

Stage 1: Interpreted Communication. (Birth to 4 months)
Stage 2: Intentional Communication (4 to 9 months)
Stage 3: Single Words (9 to 18 months)
Stage 4: Word Combinations (18 to 24 months)
Stage 5: Early Syntax (24 to 36 months)
Stage 6: Syntax Mastery (3 to 5 years)
Stage 7: Complete Generative Grammar (5 years and up)