The purpose of this study is to analyze the relation between fluency of writing and written expression for both ordinary and exceptional children. A survey of story starter test for the primary school children being made to examine the above questions. The sample were 374 students in grade one to grade three from 3 schools. The researcher and assistant researchers measured writing fluency based on the CBM method. This is a method which is using reliability and validity identified in preceding studies, whereas written expression ratings using analytic scoring. The relation between writing fluency and written expression through the correlation analysis being investigated. Also, Multiple regression analysis being used to figure out sub-indicators of written expression to represent the fluency as well. In brief, firstly, writing fluency turned out to have a high association with written expression. Secondly, the sections of contents and form among sub-indicators showed that they represented not only writing fluency but also written expression in general.
Key words : writing fluency, written expression, primary grade, writing development, writing performance assessment, quantitative assessment, qualitative assessment