A study examined the ability of subjects of varying ages to write summaries of very familiar material. In particular, it explored the subjects' planning activities both prior to and during the summarization task. The subjects, 15 fifth, 16 seventh, and 15 eleventh grade students and 11 college students, were given two stories to study for a week. They were told to concentrate on all the details in each story. At the end of this period, they were given large sheets of blank paper and told to write a summary of one of the stories. They were allowed to consult the story while writing. Results revealed that college and eleventh grade students outperformed the younger students in their propensity to plan ahead by making rough drafts of the summary, in their sensitivity to fine gradations of importance in the text, and in their ability to translate ideas into words. Planning, not age as such, was the best predictor of efficiency, although the age and propensity to plan were highly correlated. The findings suggest that when a summary is not just a measure of automatic retention, the ability to work recursively on information to render it as succinctly as possible depends on judgment and effort, as well as knowledge and strategies, and is, therefore, late developing. (FL)