A study of second language acquisition focuses on the transition from formulaic to creative speech patterns. Subjects were two native Japanese-speaking children, aged 4 and 8, learning English as a Second Language in New York, observed over a period of 2 years. The nature of formulaic speech is discussed, drawing from research on such speech and its common use in child language. Several explanations of the relationship of formulaic to creative speech is examined, concluding that routines of speech evolve into patterns, then eventually into creative speech. A process by which unanalyzed speech routines are segmented and combined with parts of other routines, thus evolving into patterns, is proposed, referring in particular to high-frequency formulas in the early language learning stages: self-assertion, imperative, demand, "I know," and "wh"-question formulas. It is suggested that this formula-based analysis leads to creative speech in dialogues in which unconscious pattern practices and substitution exercises play important roles. It is concluded that abundant use of formulaic speech in early acquisition stages reduces the learning burden while maximizing communicative capability, and progressive differentiation of formulas helps the learner build the rule system of the language. Contains 10 references. (MSE)