This paper suggests that a change in mode of expression --narrative, descriptive, or expository--can influence the syntactic complexity of children's writing. The implications of the research studies reviewed here may offer direction for education in general. Instructional strategies which make use of variation in writing mode to encourage gains in complexity may be expected to direct students toward their highest levels of performance. Among the topics discussed in this context are the influences of audience and "purpose" in writing, relevant paradigms of cognitive development and functioning, empirical evidence of developmental change, and a linguistic analogy for cognition. (KS)