Given the importance of instruction in promoting students' statistical literacy, a cohesive picture of the development of students' statistical thinking is needed to better inform classroom teachers and curriculum developers. With this in mind, one of the authors developed a framework to characterize middle school students' statistical thinking within four statistical processes, across four levels of thinking. A subsequent study (Langrall, Mooney, Hofbauer, & Johnson, 2001) addressed gaps in Mooney's framework. This paper describes how the findings of the Langrall et al. study were merged with the framework and reports on resulting modifications to the entire framework.