This paper discusses the reading diary study--a method that involves frequent observation and detailed note-taking of the strategies employed by a child while learning to read--and the problems of data reduction, limitations of methods employed by researchers, and analysis of data. The sections include "Miscue Analysis," which can be used for data reduction and which examines the techniques developed by Goodman, Weber, and Biemiller; "Soderbergh's Reading Diary Study," which discusses Soderbergh's study of her daughter's progress in Swedish from the first word at age 28 months to the first book a little over a year later and the data reduction system used; "Cognitive-Developmental Theory," which relates Piaget's notion of stages of development to when a particular strategy is employed by a child learning to read; and "Implications for Reading Diary Studies from Cognitive Theory," which discusses the importance of the reading researcher organizing diary notes on the acquisition of a specific cognitive skill--reading--into a general theory of reading acquisition. (WR)