Studies that consider the displays that students create to organize data are not common in the literature. This article compares fifth through eighth graders' difficulties with the creation of bar graphs using either raw data (Study 1, n = 155) or a provided table (Study 2, n = 152). Data in Study 1 showed statistical differences for the type of data organization but not for grade level. Students' primary problem was choosing a format that integrated a second variable and aggregating data. In contrast, in Study 2, we observed that seventh and eighth graders outperformed fifth and sixth graders. We interpret these results in terms of older students' better data interpretation competence. We conclude that students' difficulties in bar graphing can be traced to their tabulation processes. Data organization is essential for understanding and representing data, and educators should devote to it the attention it deserves.