The first section of this paper discusses recent writing research and the basic elements of language development. The second section describes a program which used a sentence-combining method as an activity-based experience for language development. A six-month study involved all fourth graders at Powell School in Mountain View, California. The students were enrolled in two classes, one taught in a traditional manner and the other taught in an open-classroom manner. The students were randomly assigned to control and experimental groups within their classes. In the experimental group, student writing was stimulated by silent cartoons and movies, by topic paragraphs, and by experiential presentations. Student writing was analyzed for quantitative features of syntactic development, and writing quality was evaluated by three teacher-writers. The results indicated that students in the experimental group made significant gains in five out of six analytic factors and the control group made significant gains in two out of six factors. The paper concludes that a grammar-free program of sentence-combining lessons, backed by games, activities, and experiential exercises, can encourage synthetic growth in the writing of fourth grade children. (TS)