To determine the normal sequence of the development of Spanish phonology and Spanish grammatical patterns in the speech of native Spanish speakers, ages 2-5, a study of the acquisition of interrogative formation was undertaken. Two male and two females from each of nine age intervals between two and five were selected as informants; all were middle-class natives of the Lower Rio Grande Valley. The subjects were interviewed 3 times each, for a total of two hours, by the author or by a female native speaker. The report of the findings, which includes a brief review of basic interrogative structures, shows that two-year-olds can distinguish between yes/no and information questions, while production lags behind comprehension. Those at 2.6 years display greater complexity in internal structure, while those at 2.9 years use "con quien,""de quien" and "cual." The next significant changes appear at 3.3 years, with V+Inf. in information questions and full tag questions. The order of acquisition is: (1) yes/no questions, (2) information WH- questions, (3) Tag questions with "verdad." The major portion of development is completed by 3.3 years. Questions requiring further investigation are proposed. (CLK)