To examine the relation between trait procrastination and the big-five factor conscientiousness in a sample of younger children, self-report scales to assess both characteristics were developed. The content of the conscientiousness measure was derived from the six facets of the factor in the Costa and McCrae (1992) model [Costa, P. T. & McCrae, R. R. (1992). Manual for the Revised NEO Personality Inventory and NEO Five-Factor Inventory. Odessa, Florida: Psychological Assessment Resources.]. The participants were 149 female and 131 male children in grades 3-5, drawn from three different schools. The scales exhibited high internal consistency. Consistent with previous research with university students, trait procrastination and conscientiousness were highly negatively related (r = -0.81). Teacher ratings of the children in their classrooms were obtained on procrastination and each of the facets of conscientiousness, with the facet ratings summed to provide a single judgment of conscientiousness. Correlations between teacher ratings and the childrens' self-report scores ranged from 0.27 to 0.37. The present study supported earlier suggestions that the proximal source of trait procrastination is the lack of conscientiousness and moves this source to an earlier stage of development.