The research reported in this paper is concerned with three questions. Are the processes of language development complete by the time children begin school? What is the order of the emergence of control of grammatical rules? And is that order similar for first and second language learners? The data used in the analysis come from a project centered at Michigan State University, which was to design an English curriculum for the children of migrant agricultural workers, most of whom spoke Spanish as a native language. A test was designed which would show what native-speaking children of eight to eleven years of age knew about their grammar. This test would then be used to select the children who were not native speakers to participate in the English program. The test was designed to cover a wide range of grammatical constructions, from the simple to the complex. The results gave the following answers to the three questions: (1) Language development is not complete by the time children begin school; (2) The order of grammatical control is as follows: possessives, present tense, past tense, negation, comparative adjectives, sentence combining, and, finally, tag questions; and (3) By and large the order of the emergence of grammatical control is similar for first and second language learners. (CFM)