The progression through the developmental stages of the acquisition of interrogatives was analyzed. Data on use of the "what" interrogative were collected during play sessions from eight children at six-month intervals from the ages of 1;6 to 3 years. More than 2,400 children's interrogatives were recorded. It was demonstrated that children's active analysis of formulas plays an important role in their discovery of syntax. A six-stage process is identified by which children progress from early interrogatives used as unanalyzed speech routines to the use of analyzed formulas and interrogative frames. This gradual process must be repeated for each interrogative word. Although early interrogatives may sound correct, they are limited and rigid in both form and use and subject to errors even after a period of seemingly correct production. The analysis necessary to recognize abstract linguistic rules is performed by children in gradual stages. (RW)